i2c and nrf52832

RE: i2c and nrf52832

Nitram — Thu, 15 Sep 2016 08:47:06 GMT

Ok, now it works, thanks. Only the debugger (Keil) shows a false value.

RE: i2c and nrf52832

Nitram — Thu, 15 Sep 2016 07:36:43 GMT

Part of the new code:

#define DEVICE_SCL_PIN 11
#define DEVICE_SDA_PIN 12

Thanks for answer!

RE: i2c and nrf52832

Nitram — Thu, 15 Sep 2016 07:34:27 GMT

When I use the nrf52 DK and change the pins, there is the same problem.

Is it a problem to change the following thing (in nrf_drv_config.h):

#define TWI0_ENABLED 0

#define TWI0_ENABLED 1

I have connected:

DK MCP9808

Udd VDD

GND GND

P0.11 SCL

P0.12 SDA

GND A0

GND A1

GND A2

RE: i2c and nrf52832

Ole Bauck — Wed, 14 Sep 2016 14:24:26 GMT

You are using P0.00 and P0.01 for TWI, these are also used for the 32KHz crystal. Probably this is why it does not work. Try changing to other pins that are not used already (check on the back of the DK).

RE: i2c and nrf52832

Nitram — Tue, 13 Sep 2016 17:18:05 GMT

I have tested it with an oscilloscope. The SDA and SCL Pins were continuous 3V. Than I have changed the pull-up to pull-down resistors, and now the clock works and I get a (wrong) signal. Maybe the capacity of the capacity is too high.

RE: i2c and nrf52832

Ole Bauck — Mon, 12 Sep 2016 11:43:14 GMT

That should not be a problem. Have you tested the code while in debug to see if the code is acting as it should and have you tested with an oscilloscope or logic analyzer attached to the lines to see if the nRF is actually trying to read the device?

RE: i2c and nrf52832

Nitram — Fri, 02 Sep 2016 09:08:46 GMT

Is it possible, that there is a problem, when I took the pointer of the m_sample into a uint8_t?

Debugger: m_sample 0x20001872 (Location)

RE: i2c and nrf52832

Nitram — Fri, 02 Sep 2016 08:57:18 GMT

The function:

err_code = nrf_drv_twi_rx(&m_twi_mcp9808, TEMP_ADDR, (uint8_t*)&m_sample, sizeof(m_sample));

does not write in the m_sample.

RE: i2c and nrf52832

Nitram — Fri, 02 Sep 2016 07:24:24 GMT

I have set pull-up on the pins, but the nothing changed. It used 100kHz.

RE: i2c and nrf52832

Ole Bauck — Wed, 31 Aug 2016 09:22:54 GMT

You can set pull-up on the pin with:

NRF_GPIO->PIN_CNF[SDA_PIN] |= (GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos);
NRF_GPIO->PIN_CNF[SCL_PIN] |= (GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos);

And you can check the NRF_GPIO->PIN_CNF[n] register if pull-up is used (see here for the register description).

Be aware that the typical value of the pull-up resistor is 13KOhm. This can work at 100kHz, but at 400KHz the pull is too weak which will result in a skewed signal on the clock line (it is an RC circuit). Recommended value for pull-up resistor on TWI is about 4.7KOhm.

RE: i2c and nrf52832

Nitram — Wed, 31 Aug 2016 06:19:15 GMT

I wanted to use the internal GPIO pull up resistors. How could I check, if they are configure?

RE: i2c and nrf52832

Ole Bauck — Tue, 30 Aug 2016 10:39:31 GMT

It is not obvious what the problem is here. I suggest that you probe the lines using a logic analyzer or oscilloscope to see if the temp sensor is actually responding.

If the device does not respond the address may be incorrect or you forgot to add external pull-up resistors.