I cannot get I2C working on contiki with the 2650 Launchpad

Matt Neu

Part Number: LAUNCHXL-CC2650

Does anyone have any suggestions on how to setup I2C on the 2650 Launchpad for contiki, the SDA and SCL pins are constant high.

over 6 years ago

0 IUsedToBeARealPerson (M-W) over 6 years ago

TI__Guru 58425 points

Hi Matt,

I will have a look and see if I can find any examples for contiki on how to setup the I2C. I'm also looping in a colleague that is more focused on the contiki platform.

0 Severin Suveren over 6 years ago

TI__Mastermind 23730 points

Hi Matt,

Are you using Contiki or Contiki-NG?

Either way, I can see to possible solutions:

Write your own I2C driver.
Use the I2C driver implementation for the sensortag platform (on Contiki)

Regarding solution #2, after quickly skimming over the existing I2C driver implementation, I don't see why it shouldn't work to simply copy/paste and modify the existing board file for the launchpad platform.

Do note however this is something you'd have to try and test for yourself. I think you'd get much more direct help by asking the Contiki community on this.

What I can identify (without trying myself) from what needs to be done to get I2C up and running on the launchpad is the following:

Copy/paste the board-i2c.h/c files from srf06-cc26xx/sensortag to srf06-cc26xx/launchpad
In Makefile.launchpad under srf06-cc26xx/launchpad: Add the new i2c files to the BOARD_SOURCEFILES variable
In board.c under srf06-cc26xx/launchpad:
1. Add a new include for board-i2c.h
2. Add a call to board_i2c_wakeup() in board_init()
3. Add a shutdown handler (just as board.c in srf06-cc26x/sensortag) which calls board_i2c_shutdown()
Recompile

Again, you are sort of on your own on this. If you do get it working by using solution #2, consider making a pull-request to the Contiki repository.

0 Matt Neu over 6 years ago in reply to Severin Suveren

Prodigy 80 points

Thanks for the responses, I have tried to get I2C working using the sensortag i2c.h/c files as suggested. I have not gotten it to work and seems to get stuck when calling the write function or even the i2c_status function.

I have resorted to using UART. I cannot get UART communication via the pins 2 and 3 that are listed in the board.h file but can get write commands out of the 2650 and readable from a PIC chip. My primary concern is that I cannot receive any information from the pic chip. This should be no different from getting info from a keyboard. So what functions are available for scanning the Rx of UART in contiki I cannot find any!?!?

0 Severin Suveren over 6 years ago in reply to Matt Neu

TI__Mastermind 23730 points

When using UART, have you made sure to register an input function to the UART driver?

e.g.

// Enable UART input by registering an input callback function
// serial_line_input_byte() is a pre-defined callback function from "dev/serial-line.h"
cc26xx_uart_set_input(serial_line_input_byte);

// Disable UART input by unregistering the input callback function
cc26xx_uart_set_input(NULL);

0 Matt Neu over 6 years ago in reply to Severin Suveren

Prodigy 80 points

Yes, but now I'm back to the I2C communication. I am resorting to creating my own code to communicate to a I2C sensor (CCS811 Air Sensor) since I cannot get the I2C code working from the sensortag.