# BM Sensor Integration - SDI-12 Multiparameter Sonde EXO3s **URL:** \ **Category:** Projects\ **Tags:** documentation\ **Created:** [August 13, 2024, 7:25pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399 "2024-08-13T19:25:58Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [August 13, 2024, 7:25pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/1 "2024-08-13T19:25:58Z")
### Introduction This blog is an ongoing attempt to be able to communicate with SDI-12 sensors. This is not as popular as a protocol but is still a standard used widely in environment data acquisition. The [Bristlemouth DevKit](https://file.notion.so/f/f/ecca0679-b04e-423c-a8e8-21cb7e08d702/021b2da3-61a4-4bd7-aa52-a98daba1a1ca/Bristlemouth_developer_kit.pdf?table=block&id=4ff803e2-7ec8-4907-b70c-8e5ab335f504&spaceId=ecca0679-b04e-423c-a8e8-21cb7e08d702&expirationTimestamp=1723665600000&signature=BwpbTJ3utjoo-mfhw-GV0DSjhEvWnnAUSO7hf2H9ETM&downloadName=Bristlemouth_developer_kit.pdf) has the terminal blocks available for SDI-12 communication. We have chosen the [YSI EXO3s Multi-parameter Sonde](https://www.ysi.com/exo3s) for this effort since it has native SDI-12 communication. This post will capture the steps, the challenges and any bugs I might come across while integrating the multi-parameter sonde EXO3s to the Bristlemouth DevKit. What is SDI-12? It’s a single data line serial communication that is widely used in environment data acquisition. It has 3 lines - GND, Data and 12VDC. Here is more information on the nitty gritty details of what makes [SDI-12 communication](https://www.sdi-12.org/index.php) ### What is my strategy? My approach to this project is pretty simple. The steps I plan to follow are - - The sensor shows up and can be connected to on a terminal on the laptop. - Send commands and receive responses. Understand the data frames coming via the SDI-12 Data line. - Wire the SDI-12 lines to the corresponding terminal blocks on the BM DevKit and see if the sensor is sending the same data frames. - Write a firmware app for the BM Mote (brains of the Bristlemouth DevKit) to send commands, receive and parse responses from the sensor to a readable format. - Spotter can receive sensor data via Bristlemouth and we can log it the the SD card and/or see it on the dashboard ### End Goal Able to integrate and communicate with an SDI-12 protocol capable sensor (Multi-parameter Sonde) via Bristlemouth. 👋 Follow along as I work on integrating a new sensor to our Bristlemouth Ecosystem! Also feel free to add comments or post any questions! ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [August 15, 2024, 12:37am UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/2 "2024-08-15T00:37:04Z")
This post documents how to wire and connect to the YSI EXO3s Multi-parameter Sonde. A note about EXO3s - it is the same as EXO3 but without a battery pack inside the housing. ## Materials - [YSI EXO3s Multi-parameter Sonde](https://www.ysi.com/exo3s) - [SDI-12 to USB adapter](https://liudr.square.site/product/sdi-12-microusb-adapter/50?cs=true&cst=custom) - 12V power supply like [this one](https://www.digikey.com/short/7ntr9qb0) - Sub connector cable with 6 conductors - Micro USB cable ![Materials](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/f2febab88e45bdd834a6207002392b10b288abf9.jpeg) ## Sensor Pinout and cable For this section, I want to wire the SDI-12 lines from the sensor to an _SDI-12 to USB adapter_ to make sure we have the pinout and wring right, and the sensor shows up as a USB port. Based on the [EXO3’s manual](https://www.ysi.com/File%20Library/Documents/Manuals/EXO-User-Manual-Web.pdf?srsltid=AfmBOoroUw1Z9GjHqVculwS4aMlodyZCqwcyhuy-9mPavuscqKIkifNh) page 30, the wiring for native SDI-12 communication is `GND` on black and bare wire, `Data` on orange wire, `12VDC` on red wire. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/e5c2190e2e0ca0ac4b5487cc3ace8fca4919b723.jpeg) Unfortunately, I don’t have the flying lead cable that is mentioned in the manual. We have a similar “subconnector” cable available but the cable colors are most likely not the same as the flying lead cable. ![Subconn cable for the sensor](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/351d4ae6a515676a905ca24fd191fc14c642e64e.jpeg) To use this cable, I need the pinout of the of the male connector on the sensor side. The YSI support team provided us with the pinout details - ![image](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/8c28ba57521274ec2b75b0fba0f85a411e4cece7.jpeg) After using a multimeter and checking which color of the subconn conductor is which pin, I figured out which color of the subconn cable wires is which SDI-12 net. Here below: | net name | pin | cable color (flying lead) | cable color (subconn) | | --- | --- | --- | --- | | SDI12 Data | 1 | orange | black | | GND | 2 & 4 | black, bare | white, green | | 12V | 3 | red | red | ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/0ee50e8c5de9d8965e8883efc1e8b27dcdad3706.jpeg) ## Wiring ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/97c4ad3e36c2be0d264ff39d7a6016d69fcee656.png) ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/dd4ce2dbbda0aafb78aa325133e58be0ea2c4317.jpeg) ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [August 15, 2024, 10:21pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/3 "2024-08-15T22:21:26Z")
## Basic SDI-12 commands and responses After wiring as mentioned above, I used `pyserial-miniterm` to find the sensor and connect to it (any serial terminal should work). I also added `echo` to view the commands I type to send. I noticed I receive the response immediately after typing `!` at the end of the command to send. Here is what I saw on the terminal. The EXO3s Multi-parameter Sonde shows up as a USB port with description: `/dev/cu.usbserial-D30FEU73 'FT231X USB UART - FT231X USB UART'` > uma@Umas-MacBook-Pro-2 ~ % pyserial-miniterm -e > — Available ports: > — 1: /dev/cu.BLTH ‘n/a’ > — 2: /dev/cu.Bluetooth-Incoming-Port ‘n/a’ > — 3: /dev/cu.usbserial-D30FEU73 ‘FT231X USB UART - FT231X USB UART’ > — Enter port index or full name: 3 > — Miniterm on /dev/cu.usbserial-D30FEU73 9600,8,N,1 — > — Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H — > ␀?!0 > 0!0 > 0I!013YSIIWQSGEXOSND100 > 0M!00629 > 0 > 0D!0 > 0D0!0+0.098+22.783+5.50+6.87 > 0D1!0-7.13+83.10+7.16+5.95 > 0D2!0+1.22+12.41 > 0D3!0 ### Breaking it down - I used [this website](https://help.campbellsci.com/cs650-cs655/shared/sdi-12-sensor-support/sdi-12-command-basics.htm?tocpath=SDI-12%20sensor%20support%7CSDI-12%20command%20basics%7C _____ 0) to look up SDI-12 commands since it’s easy to read. | command | response | interpretation | | --- | --- | --- | | ?! | 0 | _Address Query:_ `0` is the address | | 0! | 0 | _ACK:_ `0` is the address | | 0I! | 013YSIIWQSGEXOSND100 | _Identification:_ `0` sdi-12 sensor address; `13` sdi-12 version number; `YSIIWQSG` vendor identification; `EXOSND` sensor model; `100` sensor version | | 0M! | 00629 | _Measure command:_ `0` sdi-12 sensor address; `062` time is seconds until data available; `9` number of value to expect after `62` seconds (`0` will be rxd to indicate measurement is done) | | 0D0! | 0+0.098+22.783+5.50+6.87 | _Send Data command from channel `0`:_ `0` sdi-12 sensor address; `0.098` value 1; `22.783` value 2; `5.50` value 3; `6.87` value 4 | | 0D1! | 0-7.13+83.10+7.16+5.95 | _Send Data command from channel 1:_ `0` sdi-12 sensor address; `-7.13` value 5; `83.10` value 6; `7.16` value 7; `5.95` value 8 | | 0D2! | 0+1.22+12.41 | _Send Data command from channel 2:_ `0` sdi-12 sensor address; `1.22` value 9; `12.41` value 10? | ## Next Steps The next step is understanding this data. Some questions that came up after getting this data – - What do the values mean? - In what order are they being sent? - Can I configure them and choose which reading is sent first? - Does the position of the sensors inside the sonde matter? After having a little back and forth with the YSI support team, I understand I would need to use their [Kor Software](https://www.ysi.com/kor-software?srsltid=AfmBOooZaQwozooXZNvleUYCPGRilUQ6M3KCeeDsx6LhFcQF7BlGq4dA) and along with their [DCP Signal Output Adapter](https://www.ysi.com/product/id-599820/exo-dcp-signal-output-adapter-2-0?srsltid=AfmBOoosiYI6nhYcufGQ16CVrvBbJaS9DAWwe0eIfWWYGEako0ygBLl7) to configure the data frames being sent from the sonde. My next post will be about my discoveries using the Kor software + DCP SOA with the EXO3s. ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 3, 2024, 6:48pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/4 "2024-11-03T18:48:02Z")
# Sonde Data format ### Sensors inside the EXO3s Multi-parameter Sonde I have are ```auto 1. pH 2. Wiped Cond/T 3. Turbidity 4. Optical DO 5. Central Wiper ``` ## Kor Software To figure out the value sequence being output from the EXO3s Multi-parameter Sonde, it is crucial to view the sensor on the [Kor Software](https://www.ysi.com/kor-software?srsltid=AfmBOooZaQwozooXZNvleUYCPGRilUQ6M3KCeeDsx6LhFcQF7BlGq4dA). The sonde will be discoverable via bluetooth on the Kor Software on power up (flashing blue light). The sonde shows up like this on the software. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/2898ac388c4741d5cd44e7a42e22a77fc8e614a3.jpeg) ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/6e2bca6346b38527e6580e787c0aac18a65a6c26.png) On the `Deployments` tab, I clicked on `Create Template from Sonde`. This opens a dialogue box with the current configurations. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/3f4221415a96544b474d2ec80bf1b6cfd7f402b6.png) The `DCP ADAPTER OUTPUT` subsection has the SDI-12 relevant settings. The SDI-12 slave address is `0` and the sequence of the values can be set here on the right side. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/d865cfc5292d43849ecf4af00b39fd0442af1983.jpeg) I made a note of this sequence for the example firmware app I am developing for this sensor. ### Sequence of data values from the EXO3s ```auto 1. Temperature (° Celcius) 2. Sp Cond (µS/cm) 3. pH 4. pH (mV) 5. Dissolved Oxygen (% Sat) 6. Dissolved Oxygen (mg/L) 7. Turbidity (NTU) 8. Wiper position (V) 9. Depth (m) 10. Sonde Cable Power (V) ``` ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 4, 2024, 5:57pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/5 "2024-11-04T17:57:10Z")
# Using Bristlemouth Development board ## Wiring the sonde to the Development board - The dev board has terminal blocks available for SDI-12 communication. I wired the SDI-12 wires to the appropriate terminal blocks - `12V` to `SDI 12V`, `DATA` to `SDI DATA` and both the GND wires to the `GND` terminal blocks. ![EXO3s SDI-12 wiring](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/ab287bf4431917c0b07ef3e2fcadbd17dd447fb4.jpeg) ![Sensor wired to the Dev board](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/5b57e4947a38554ffe854381a1ec93b6272b62c4.jpeg) - The jumpers also need to be placed on the bottom side of the board to configure SDI-12 comm ![Blue jumpers](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/527ab7c5d5c633b6184c878cee36f1ae1eb00aa3.jpeg) # Creating an example app for SDI-12 I made a branch in the `bm_protocol` repository - [sdi12\_example](https://github.com/bristlemouth/bm_protocol/tree/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example). The [SDI-12 Specifications](https://www.sdi-12.org/current_specification/SDI-12%20Specification%201.4%20February%2020%202023.pdf) state that the protocol needs these settings - - Transmissions ASCII characters - Baud rate needs to be set to `1200` - Data Frame configurations - 1 start bit - 7 data bits - 1 even parity bit - 1 stop bit - Serial line is negative logic - Before sending a command, it needs a `break` (data line held HIGH for 12 ms) and `mark` (data line held LOW for 9 ms) The next post will have more details on the code changes I made to add these specs! ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 5, 2024, 2:01am UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/6 "2024-11-05T02:01:02Z")
# SDI-12 protocol in the firmware app I have created the library files required for the EXO3s communication - [exo3s\_sensor.cpp](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example/user_code/exo3s_sensor.cpp) and [exo3s\_sensor.h](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example/user_code/exo3s_sensor.h) along with [user\_code.cpp](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example/user_code/user_code.cpp) and [user\_code.h](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example/user_code/user_code.h) files in my branch based off of the [serial\_payload\_example](https://github.com/bristlemouth/bm_protocol/tree/develop/src/apps/bm_devkit/serial_payload_example). ## Setting the Baud rate to `1200` Within the `init()` in the `exo3s_sensor.cpp`, this is what I added to set the baud rate to 1200. `BAUD_RATE` is defined to be 1200. ```auto PLUART::setBaud(BAUD_RATE); ``` ## Data Frame configurations By default, the settings for the LPUART are - 1 start bit, 8 data bits, no parity bit, 1 stop bit. But we need to change this. The only successful way to configure it in this way is to set this in the Lower Level files - [usart.c](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/bsp/bm_mote_v1.0/Core/Src/usart.c) (_ **Note** : This is not the right way to do it since I am editing a `bsp`, board support package, file_) Within the `MX_LPUART1_UART_Init()`, these are the configs I changed to set the LPUART to 1 start bit, 7 data bits, 1 even parity bit, 1 stop bit ```auto LPUART_InitStruct.DataWidth = LL_LPUART_DATAWIDTH_8B; // including the parity bit LPUART_InitStruct.Parity = LL_LPUART_PARITY_EVEN; ``` ## Serial line is negative logic The data line is negative logic and it has to be inverted. I added this in the same `MX_LPUART1_UART_Init()` function. ```auto LL_LPUART_SetTXPinLevel(LPUART1, LL_LPUART_TXPIN_LEVEL_INVERTED); ``` ## Break and Wake command Before sending a command, the protocol expects a `break` (data line held HIGH for 12 ms) and `mark` (data line held LOW for 9 ms). This is a pretty crucial step and took me some time to figure out. After some debugging and using the Saleae logic analyzer, this was the way to achieve that. For a short amount of time, the TX pin needs to multiplexed to be a GPIO output after disabling UART. Setting TX pin to HIGH for 12 ms break, followed by setting it to LOW for 9 ms and then multiplexing the TX pin back to GPIO ALTERNATE. ```auto void SondeEXO3sSensor::sdi_break_mark(void) { flush(); uint32_t timeStart; PLUART::disable(); //Set TX pin to output PLUART::configTxPinOutput(); // HIGH at TX pin PLUART::setTxPinOutputLevel(); // Break - hold HIGH for 12 ms timeStart = uptimeGetMs(); while(uptimeGetMs() - timeStart < breakTimeMin); // LOW at TX pin PLUART::resetTxPinOutputLevel(); // Mark - hold LOW for 9 ms timeStart = uptimeGetMs(); while(uptimeGetMs() - timeStart < markTimeMin); // Set TX pin back to TX (alternate) mode PLUART::configTxPinAlternate(); // Re-enable UART PLUART::enable(); } ``` This `sdi_break_mark()` is used in the `sdi_transmit()` funciton before sending each command. ```auto void SondeEXO3sSensor::sdi_transmit(const char *ptr) { // TX enable PLUART::startTransaction(); sdi_break_mark(); PLUART::write((uint8_t *)ptr, strlen(ptr)); // TX disable PLUART::endTransaction(100); } ``` Here, `startTransactions()` and `endTransactions()` is to enable and disable the `OE` line (output enable). ## SDI-12 Commands and Responses - **Inquiry Command** - is sent to get the sensor address - **Identification Command** - is sent to get the identification string from the sensor - **Measure Command** - is sent to ask the sensor to start measurements. - **Data Command** - is sent to retrieve the new data. ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 5, 2024, 9:40pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/7 "2024-11-05T21:40:35Z")
In this post, I am adding screenshots of how the SDI-12’s data line looks when a command is sent and the response it receives on the same data line. I’m using the [Saleae Logic Analyzer](https://www.saleae.com/products/saleae-logic-8) with it’s [Logic 2 software](https://www.saleae.com/pages/downloads?srsltid=AfmBOornxQvzMflkLlHMpD0pUs0QThulM5L5FR0GqAGJtocNH3s4wtkk) to do this. ## Saleae Logic Analyzer filter settings The Async Serial filter settings are - **1200** baud, **7 bits per** transfer, **1 stop** bit, **1 even** parity bit, **LSB** first, Signal **Inverted** ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/2bf453d1afb607e6c1507d6eb846993c9cb31134.jpeg) ## Command to get the slave address - `?!` Response is `0\r\n`. `0` is the sensor address. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/b92915ecf17f8d8d41459149500d6ff69e209f08.png) ## Command to get the identification string - `0I!` Response is `013YSIIWQSGEXOSND100\r\n`. `0` sdi-12 sensor address; `13` sdi-12 version number; `YSIIWQSG` vendor identification; `EXOSND` sensor model; `100` sensor version; ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/734ad15541e9c3f435961097f43110900f1e58ba.png) ## Measure Command - `0M!` Response is `00629\r\n`. `0` sdi-12 sensor address; `062` time is seconds until data available; `9`+1 number of value to expect after `62` seconds; ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/d44ce19604aee416a28b3e402d59cf0ca642eb06.png) After 62 seconds, the sensor sends over a `0\r\n` to indicate the measurement is done. And now we can inquire values using the data commands. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/e49d53923166fcc81574d48bd2f29d42a209def3.jpeg) ## Data Commands - `0D0!`, `0D1!`, `0D2!` Response to `0D0!` is `0+21.501+5.88+7.17-24.00\r\n`. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/fa49e6f0e649d0ef75b772cc28ac687be87d41d3.png) Response to `0D1!` is `0+102.62+9.06+13.56+1.22\r\n`. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/aa1cbcbd62e3eb08f43b2d32a6b6f372b47c9b4c.png) Response to `0D2!` is `0+0.251+12.12\r\n`. ![](https://canada1.discourse-cdn.com/flex029/uploads/bristlemouth/original/1X/41464f3dd03dff68b30d44e166f7dd079371f7ff.png) ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 8, 2024, 10:15pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/8 "2024-11-08T22:15:21Z")
For this section where I mentioned I had to edit a bsp file, I found a better way to do it where we don’t have to touch the bsp `usart.c` file. > [@umakat](#): > > The only successful way to configure it in this way is to set this in the Lower Level files - [usart.c](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/bsp/bm_mote_v1.0/Core/Src/usart.c) > (_ **Note** : This is not the right way to do it since I am editing a `bsp`, board support package, file_) Resolved this by adding 2 functions in `payload_uart.cpp` to set the even parity bit and invert the data. I needed to disable LPUART, configure the parameter and enable LPUART — ```auto void setEvenParity(void){ LL_LPUART_Disable(static_cast(uart_handle.device)); LL_LPUART_SetParity(static_cast(uart_handle.device), LL_LPUART_PARITY_EVEN); LL_LPUART_Enable(static_cast(uart_handle.device)); } void enableDataInversion(void){ LL_LPUART_Disable(static_cast(uart_handle.device)); LL_LPUART_SetTXPinLevel(static_cast(uart_handle.device), LL_LPUART_TXPIN_LEVEL_INVERTED); LL_LPUART_Enable(static_cast(uart_handle.device)); } ``` ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 8, 2024, 11:50pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/9 "2024-11-08T23:50:28Z")
# Defining `struct` based on the sensors in the EXO3s MP Sonde The EXO3s Multiparameter Sonde I am workign with is installed with _pH_, _Wiped Condensation/Temperature_, _Turbidity_, _Optical Dissolved Oxygen_ and _Central Wiper_ sensors inside. And the Kor Software helps define the sequence of the values on the SDI-12 data frames (as mentioned in the [post](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/3#p-1350-sonde-data-format-1) above) Therefore, the `struct` in the `sdi12_example` app is defined accordingly – - In `exo3_sensor.h` file, ```auto struct __attribute__ ((packed)) EXO3sample { float temp_sensor; // Celcius float sp_cond; // uS/cm float pH; float pH_mV; // mV float dis_oxy; // % Sat float dis_oxy_mg; // mg/L float turbidity; // NTU float wiper_pos; // volt float depth; // meters float power; // volt }; ``` - In `exo3_sensor.cpp` file, within `sdi_cdd()` case 2, the 3 data frames’ responses are populated to the appropriate struct variables — - `0D0!` - `0D1!` - `0D2!` ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [November 9, 2024, 1:37am UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/10 "2024-11-09T01:37:55Z")
# Connecting the Dev Board to the Spotter ## Spotter + Dev board Setup I disconnected to 24V power supply to the Dev Board stack and instead wired it to the spotter using the 2 conductor cable. To set up the Spotter, I needed to adjust some configurations to ensure it could continuously power the Dev board stack for development purposes. Screened into the Spotter via `pyserial-miniterm` and viewed the configs by typing `bm cfg status 0 s` (0 is the node ID) – ```auto bm cfg status 0 s Succesfull status request send 2024-11-04T19:17:56.179Z [BRIDGE_CFG] [INFO] Response msg -- Node Id: 0000000000000000, Partition: system, Commit Status: 0 2024-11-04T19:17:56.179Z [BRIDGE_CFG] [INFO] Num Keys: 15 2024-11-04T19:17:56.179Z [BRIDGE_CFG] [INFO] Key 0: bridgePowerControllerEnabled 2024-11-04T19:17:56.179Z [BRIDGE_CFG] [INFO] Key 1: sampleIntervalMs 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 2: sampleDurationMs 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 3: dfu_confirm 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 4: subsampleIntervalMs 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 5: subsampleDurationMs 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 6: subsampleEnabled 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 7: alignmentInterval5Min 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 8: samplesPerReport 2024-11-04T19:17:56.183Z [BRIDGE_CFG] [INFO] Key 9: transmitAggregations 2024-11-04T19:17:56.187Z [BRIDGE_CFG] [INFO] Key 10: currentReadingPeriodMs 2024-11-04T19:17:56.187Z [BRIDGE_CFG] [INFO] Key 11: softReadingPeriodMs 2024-11-04T19:17:56.187Z [BRIDGE_CFG] [INFO] Key 12: rbrCodaReadingPeriodMs 2024-11-04T19:17:56.187Z [BRIDGE_CFG] [INFO] Key 13: ticksSamplingEnabled 2024-11-04T19:17:56.187Z [BRIDGE_CFG] [INFO] Key 14: turbidityReadingPeriodMs 2024-11-04T19:17:56.195Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 0 2024-11-04T19:17:56.203Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 3600000 2024-11-04T19:17:56.210Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 310000 2024-11-04T19:17:56.214Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 0 2024-11-04T19:17:56.222Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 60000 2024-11-04T19:17:56.230Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 30000 2024-11-04T19:17:56.238Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 0 2024-11-04T19:17:56.242Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 1 2024-11-04T19:17:56.250Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 1 2024-11-04T19:17:56.257Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 1 2024-11-04T19:17:56.261Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 60000 2024-11-04T19:17:56.269Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 500 2024-11-04T19:17:56.277Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 500 2024-11-04T19:17:56.281Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 0 2024-11-04T19:17:56.289Z [BRIDGE_CFG] [INFO] Node ID: 0000000000000000 Partition: system Value: 1000 ``` We need to set `bridgePowerControllerEnabled` to be **0** to constantly power the dev board stack - **`bm cfg set 0 s u bridgePowerControllerEnabled 0`** # Retrieving raw data I used the `curl` command to query raw data from the API ```auto curl "https://api.sofarocean.com/api/raw-messages?spotterId=SPOT-30824C&startDate=DATET00:00:00Z" -H 'token: YOUR-API-TOKEN' | jq . ``` I installed the `jq` package to display the raw data in a more readable format. Fill out the YOUR-API-TOKEN and DATE before running this command. Raw data from the BM payload will have a header `de` and an example will look like this — ```auto { "momsn": null, "transmitTime": "2024-11-04T18:40:51.000Z", "approxLon": "-122.39", "approxLat": "37.79", "cep": null, "message": "de672915349f7ca0123536d80006d40000caf3e2ef0ef2e488fabb7c18ba49a54185ebd1407b14e640b81ec7c1c375cd421f851341713d064148e19a3f3d0a573e85eb4141ee7ca5417b14ce40f628e4405c8facc1a470cd421f85134152b8024148e19a3f6210583e85eb4141fca9a541ae47c9400ad7e3406666a8c1c375cd42295c13419a990d41f6289c3fac1c5a3e85eb4141", "createdAt": "2024-11-04T18:41:13.396Z", "messageHeader": 222, "counter": null, "partNo": null, "processed": true, "commSource": "cellular", "processingSource": "embedded" } ``` Here the raw data is **de672915349f7ca0123536d80006d40000caf3e2ef0ef2e488fabb7c18ba49a54185ebd1407b14e640b81ec7c1c375cd421f851341713d064148e19a3f3d0a573e85eb4141ee7ca5417b14ce40f628e4405c8facc1a470cd421f85134152b8024148e19a3f6210583e85eb4141fca9a541ae47c9400ad7e3406666a8c1c375cd42295c13419a990d41f6289c3fac1c5a3e85eb4141** # Decoding the raw data I made a simple script to interpret and decode the raw data. Here is the script - [exo3\_sdi12\_decoder.py](https://github.com/bristlemouth/bm_protocol/blob/uma/sdi12_sonde/src/apps/bm_devkit/sdi12_example/exo3_sdi12_decoder.py). I have an example raw data stored in a variable called `payload` in the script. The raw data is decoded and displayed – ```auto (bristlemouth) uma@Umas-MacBook-Pro-2 sdi12_example % python3 exo3_sdi12_decoder.py - Detection data: temp_sensor: 22.9689998626709 sp_cond: 5.769999980926514 pH: 7.090000152587891 pH_mV: -19.649999618530273 dis_oxy: 103.73999786376953 dis_oxy_mg: 8.899999618530273 turbidity: 13.399999618530273 wiper_pos: 1.2100000381469727 depth: 0.30399999022483826 power: 12.119999885559082 --------------------------------- - Detection data: temp_sensor: 22.97800064086914 sp_cond: 5.829999923706055 pH: 7.090000152587891 pH_mV: -19.670000076293945 dis_oxy: 103.73999786376953 dis_oxy_mg: 8.899999618530273 turbidity: 13.220000267028809 wiper_pos: 1.2000000476837158 depth: 0.30399999022483826 power: 12.119999885559082 --------------------------------- - Detection data: temp_sensor: 22.98699951171875 sp_cond: 5.650000095367432 pH: 7.090000152587891 pH_mV: -19.579999923706055 dis_oxy: 103.7300033569336 dis_oxy_mg: 8.899999618530273 turbidity: 13.619999885559082 wiper_pos: 1.2100000381469727 depth: 0.3050000071525574 power: 12.119999885559082 --------------------------------- ``` ---
**Author:** ![umakat](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/umakat/32/215_2.png) [@umakat](https://bristlemouth.discourse.group/u/umakat)\ **Post date:** [July 10, 2025, 11:47pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/11 "2025-07-10T23:47:38Z")
🎉 Exciting news – An official guide to integrate an SDI-12 sensor (YSI EXO3s Sonde) via Bristlemouth has been released! 🎉 ## [Bristlemouth Dev Kit Guide: Integrating an SDI-12 Serial Sensor](https://bristlemouth.notion.site/dev-kit-guide-integrating-an-sdi-12-serial-sensor) ---
**Author:** ![zack\_j](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/zack_j/32/13_2.png) [@zack\_j](https://bristlemouth.discourse.group/u/zack_j)\ **Post date:** [July 18, 2025, 9:04pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/12 "2025-07-18T21:04:25Z")
Amazing! I’m certain a few people here would love to read this! ---
**Author:** ![zachary](https://yyz1.discourse-cdn.com/flex029/user_avatar/bristlemouth.discourse.group/zachary/32/31_2.png) [@zachary](https://bristlemouth.discourse.group/u/zachary)\ **Post date:** [March 30, 2026, 3:43pm UTC](https://bristlemouth.discourse.group/t/bm-sensor-integration-sdi-12-multiparameter-sonde-exo3s/399/13 "2026-03-30T15:43:51Z")
Just wanted to link to a recent follow-up topic about analyzing and visualizing the data collected from a real exo3 sonde deployment: [Decoding data (EXO3) that is sent from the dev kit to the Sofar Spotter dashboard - #6 by zachary](https://bristlemouth.discourse.group/t/decoding-data-exo3-that-is-sent-from-the-dev-kit-to-the-sofar-spotter-dashboard/561/6) Top 2 links from that thread if you don’t click through: - Updated link to the python parsing script [exo3\_sdi12\_decoder.py](https://github.com/bristlemouth/bm_protocol/blob/23d4ff18a4704a1c0e3e80362f6855713149b31e/src/apps/bm_devkit/sdi12_example/exo3_sdi12_decoder.py) since the one above in this topic is out of date - New html file where you can drag and drop the CSV downloaded from the Spotter dashboard and get charts and a downloadable CSV of the parsed sonde readings for all parameters: [exo3-sonde-data-viewer.html](https://github.com/bristlemouth/bm_protocol/blob/23d4ff18a4704a1c0e3e80362f6855713149b31e/src/apps/bm_devkit/sdi12_example/exo3-sonde-data-viewer.html)