TWI Does not work

RE: TWI Does not work

Nasib — Tue, 04 May 2021 14:00:53 GMT

Ok, now i can see that setting m_xfer_done to true the system sends a command each 0,8s more or less... What m_xfer_done does? Does it is set to true when the master receive an ACK? Why if i force this variable to true it sends periodically a command?

In my real application i want to use this twi with:

Soft device (Timer 0) for BLE_UART
Timer 1: interruption
Timer 2: pwm

If i copy the twi code to my real app... it does not generate any command even if i force m_xfer_done to true. Is there any conflict with the resources i mention before?

Thanks a lot!

RE: TWI Does not work

Nasib — Tue, 04 May 2021 13:40:30 GMT

RE: TWI Does not work

Håkon Alseth — Tue, 04 May 2021 12:50:17 GMT

Here's my scope when triggering on SDA line:

I used internal pullup in the GPIO. Since you use 2.5kOhm, you sink ~1 mA, which might require you to setup the GPIOs in high-drive mode (See NRF_GPIO->PIN_CNF[] register). You could try a bit of a weaker pull-resistor, but you should still see something on your oscilloscope just after reset.

for testing purposes: You could also set m_xfer_done=true in function main.c::twi_handler(), regardless of event received. This will then send every ~0.5 second.

Kind regards,

Håkon

RE: TWI Does not work

Nasib — Tue, 04 May 2021 11:42:20 GMT

I have reduced the problem to the minimum now:

I am using sdk12 3 twi_sensor example
I am using pca10028 board
I have installed a 2,5k pull up resistor from gpio07 to vcc
I have installed a 2,5k pull up resistor form gpio30 to vcc

I have no sensor connected now. I load the example and i see absolutely nothing in the scope...

I have reset the device but even with this i can not see anything...

RE: TWI Does not work

Håkon Alseth — Tue, 04 May 2021 11:07:07 GMT

The program will send one transfer, wait for a successful event, then do another.

If the transfer is not successful, it will send one transaction and then hang forever. This is the reason why I asked if you could reset the device and capture the trace and see if you get any output on SCL/SDA pins. Regardless, this points towards a issue with addressing the i2c sensor. Please doublecheck that the i2c address is correct, and please verify that the i2c master sends anything on boot-up.

Kind regards,

Håkon

RE: TWI Does not work

Nasib — Tue, 04 May 2021 09:14:01 GMT

Thanks for your answer. What happens here is that even if I send the command in the main endless loop I am not able to see anything in the scope. Anything, no a single bit. And of course not a single ack.

Is there any pre configuration that I should do to use this example ?

RE: TWI Does not work

Håkon Alseth — Tue, 04 May 2021 09:03:00 GMT

But, does it ACK the command you send? If you scope the initial communication, you should be able to see if the ACK bit is set or not.

Kind regards,

Håkon

RE: TWI Does not work

Nasib — Mon, 03 May 2021 13:02:57 GMT

Yes there is a sensor connected. But even with the sensor or with out i dont see any comand sent with my oscilloscope

RE: TWI Does not work

Håkon Alseth — Mon, 03 May 2021 12:03:47 GMT

Hi,

If nothing is connected, then it only sends one command and waits for an ACK in the twi_handler.

Try power cycling your nrf and see if it initially sends one transaction.

Kind regards,

Håkon