i2c support for Teensy 4.1

[TimRedfern]

Hi,

I'm trying to use i2c with teensy 4.1 and running into some problems.

I'm trying to write data in master mode. I'm seeing the same problem with the master_writer sample for Teensy 4.1 that ships with Teensyduino, and my code.

I'm not what the status is of support for the Wire library for the newest Teensy as this page is the only info I can find about compatibility and does not mention Teensy 4.x: https://www.pjrc.com/teensy/td_libs.html

When I upload the master_writer sample, and monitor pins 18 and 19, I see the i2c address being transmitted, but no data is being written.

Expected result: The i2c address would be written, then a number of bytes of data ("x is 1"). The clock signal should transmit 64 or more pulses.

Actual result: Just the i2c address is written. The clock only transmits 8 pulses.

Has anyone had any success using i2c with Teensy 4.x, or can comment about the status of i2c support from the Teensyduino libraries?

Thanks in advance.

Tim

 

[jonr]

> Actual result: Just the i2c address is written. The clock only transmits 8 pulses.

i2c on t4 works fine.

Here is a relevant quote from a description of the protocol:

"Each byte of data (including the address byte) is followed by one ACK bit from the receiver. The ACK bit
allows the receiver to communicate to the transmitter that the byte was successfully received and another
byte may be sent."

 

[TimRedfern]

Ah yes, my receiver chip has to acknowledge before the next byte is written. Sorry for the confusion!

 

[TimRedfern]

> Actual result: Just the i2c address is written. The clock only transmits 8 pulses.

i2c on t4 works fine.

It's working now, thanks for your help!