I2C initialization on registers level

RE: I2C initialization on registers level

Leonid.K. — Tue, 23 Mar 2021 17:17:16 GMT

Looks like you right.

It should be

It works now.

Thanks a lot.

RE: I2C initialization on registers level

Jørgen Holmefjord — Tue, 23 Mar 2021 16:30:15 GMT

Did you verify that the PSEL registers got set correctly? I'm not sure about how your masks work, but my point was that you need to set the registers to 0x0000001E and 0x00000007 to get correct behavior.

RE: I2C initialization on registers level

Leonid.K. — Mon, 22 Mar 2021 06:55:17 GMT

So, on pic 1 shown how it should be,

and here what I have by a first running after working code:

Please pay attention to low SCK level (why?) and NACK with the same slave address.

The repeated run causes to falling LOW the SDA line.

RE: I2C initialization on registers level

Leonid.K. — Mon, 22 Mar 2021 05:43:37 GMT

The SCL line goes HIGH, and SDA line remains LOW.

If I run code specially written for I2C, I see correct lines activities.

RE: I2C initialization on registers level

Leonid.K. — Mon, 22 Mar 2021 05:07:42 GMT

Dear Jorgen,

Thanks a lot for your answer.

But it still doesn't work for me.

I did exactly what you mentioned:

But still don't see any activity on SDA, SCL lines.

May be something else need?

Best regards.

Leonid.

RE: I2C initialization on registers level

Jørgen Holmefjord — Sun, 21 Mar 2021 15:40:19 GMT

Hi,

0xBFFFFFFF and 0xFFFFFF7F is not valid values in the PSELSDA/PSELSCL registers. These registers should be set to the GPIO pin number (0x7 and 0x1E in your case), of 0xFFFFFFFF in case the pin is Disconnected:

The address register should also be set before starting the transfer.

I verified that these commands works with nrfjprog:

nrfjprog --memwr 0x40003500 --val 0x00000000
nrfjprog --memwr 0x50000778 --val 0x00000302
nrfjprog --memwr 0x5000071c --val 0x0000060C
nrfjprog --memwr 0x40000528 --val 0x00000009
nrfjprog --memwr 0x4000350c --val 0x1E
nrfjprog --memwr 0x40003508 --val 0x7
nrfjprog --memwr 0x40003524 --val 0x01980000
nrfjprog --memwr 0x40003500 --val 0x00000005
nrfjprog --memwr 0x40003588 --val 0x00000055
nrfjprog --memwr 0x40003008 --val 0x00000001

This generates the following output on the pins:

Best regards,
Jørgen

RE: I2C initialization on registers level

Leonid.K. — Sat, 13 Mar 2021 10:28:05 GMT

I tried following:

//# TWI DISABLE

#prog -o cmd -c write -t h40003500 -l 4 --data h00000000 --mask h00000007
#prog -o cmd -c compare -t h40003500 -l 4 --data h00000000 --mask h00000007

//# SET IO PINS CONFIGURATION SDA (P30)

#prog -o cmd -c write -t h50000778 -l 4 --data h00000302 --mask h0003070F
#prog -o cmd -c compare -t h50000778 -l 4 --data h00000302 --mask h0003070F

//# SET IO PINS CONFIGURATION SCL (P7)
#prog -o cmd -c write -t h5000071c -l 4 --data h0000060C --mask h0003070F
#prog -o cmd -c compare -t h5000071c -l 4 --data h0000060C --mask h0003070F

//# Classify SPI0 and TWI0 as region 0 peripheral
#prog -o cmd -c write -t h40000528 -l 4 --data h00000009 --mask h00000009
#prog -o cmd -c compare -t h40000528 -l 4 --data h00000009 --mask h00000009

//# SET PIN FOR SDA (PSELSDA)
#prog -o cmd -c write -t h4000350c -l 4 --data hBFFFFFFF --mask hFFFFFFFF
#data -o set -c out -t file -f \images\TWI0_TWI_PSELSDA.bin
#prog -o cmd -c read -m ram -s h0 -t h4000350c -l 4

Here I read 0xFFFFFFFF instead of expected 0xBFFFFFFF

//# SET PIN FOR SCK (PSELSCL)
#prog -o cmd -c write -t h40003508 -l 4 --data hFFFFFF7F --mask hFFFFFFFF
#data -o set -c out -t file -f \images\TWI0_TWI_PSELSCL.bin
#prog -o cmd -c read -m ram -s h0 -t h40003508 -l 4

Here I read 0xFFFFFFFF instead of expected 0xFFFFFF7F

# TWI frequency settings
#prog -o cmd -c write -t h40003524 -l 4 --data h01980000 --mask h07F80000
#prog -o cmd -c compare -t h40003524 -l 4 --data h01980000 --mask h07F80000

//# TWI ENABLE
#prog -o cmd -c write -t h40003500 -l 4 --data h00000005 --mask h00000007
#prog -o cmd -c compare -t h40003500 -l 4 --data h00000005 --mask h00000007

//# Start TWI transmit sequence
#prog -o cmd -c write -t h40003008 -l 4 --data h00000001 --mask h00000001
#prog -o cmd -c compare -t h40003008 -l 4 --data h00000001 --mask h00000001

//# TWI SLAVE ADDRESS
#prog -o cmd -c write -t h40003588 -l 4 --data h00000055 --mask h0000007F
#prog -o cmd -c compare -t h40003588 -l 4 --data h00000055 --mask h0000007F

Sure I don't see by scope any lines activities.

What wrong?

RE: I2C initialization on registers level

Nguyen Hoan Hoang — Sun, 28 Feb 2021 15:47:55 GMT

you can download the data sheet from https://infocenter.nordicsemi.com/index.jsp. It contains all the information you need.