Just for completeness, I2C1 module seems correctly active and working:
root@beaglebone:~# i2cdetect -l
i2c-0 i2c OMAP I2C adapter I2C adapter
i2c-1 i2c OMAP I2C adapter I2C adapter
i2c-2 i2c OMAP I2C adapter I2C adapter
I2C1 module was mapped on i2c-2 (nothing new here) as we can see from the
base address 4802a000:
root@beaglebone:~# ls /sys/class/i2c-dev/ -l
total 0
lrwxrwxrwx 1 root root 0 Jan 1 2000 i2c-0 ->
../../devices/ocp.3/44e0b000.i2c/i2c-0/i2c-dev/i2c-0
lrwxrwxrwx 1 root root 0 Jan 1 2000 i2c-1 ->
../../devices/ocp.3/4819c000.i2c/i2c-1/i2c-dev/i2c-1
lrwxrwxrwx 1 root root 0 Jul 19 09:57 i2c-2 ->
../../devices/ocp.3/4802a000.i2c/i2c-2/i2c-dev/i2c-2
And the devices are correctly attached to the bus (2x MCP23017):
root@beaglebone:~# i2cdetect -r 2
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-2 using read byte commands.
I will probe address range 0x03-0x77.
Continue? [Y/n]
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 21 -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
0x20 and 0x21 are the address of the 2 I/O expanders, as expected.
I also look at the SDA and SCL pins (with a scope) during the bus scan and
both clock and data signals seems good (I notice 100kHz clock is used).
All is working well... so why I still can't correctly access the I2C1
module by PRU?
Il giorno sabato 18 luglio 2015 23:41:22 UTC+2, Gianfranco Rosso ha scritto:
>
> I finally installed CCS6 and use USB100v2 JTAG interface (after soldering
> the header into BBB pads).
>
> It looks like as I2C1 module never goes out of reset status: RDONE flag
> into I2C_SYSS register is always 0 even after writing I2C_EN=1 into I2C_CON
> register (and also, SRST=0 into register I2C_SYSC).
> The very odd thing is that if I read register I2C_CON it results 0, as if
> the SBCO instruction didn't write it effectively.
>
> Is there some write-protect lock to deal with?
>
>
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