i2c multi master

2020-02-27T15:33:45.758000Z

Okay ... I stand corrected.

However, although it seems there's a second I2C interface available on RPi hardware when you issue the gpio readall command:

pi@raspberrypi:~ $ ls /dev/i2c*
/dev/i2c-1
pi@raspberrypi:~ $ gpio readall
 +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
 |   2 |   8 |   SDA.1 | ALT0 | 1 |  3 || 4  |   |      | 5v      |     |     |
 |   3 |   9 |   SCL.1 | ALT0 | 1 |  5 || 6  |   |      | 0v      |     |     |
 |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 0 | IN   | TxD     | 15  | 14  |
 |     |     |      0v |      |   |  9 || 10 | 1 | IN   | RxD     | 16  | 15  |
 |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 0 | IN   | GPIO. 1 | 1   | 18  |
 |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
 |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
 |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
 |  10 |  12 |    MOSI | ALT0 | 0 | 19 || 20 |   |      | 0v      |     |     |
 |   9 |  13 |    MISO | ALT0 | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
 |  11 |  14 |    SCLK | ALT0 | 0 | 23 || 24 | 1 | OUT  | CE0     | 10  | 8   |
 |     |     |      0v |      |   | 25 || 26 | 1 | OUT  | CE1     | 11  | 7   |
 |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
 |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
 |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
 |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
 |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
 |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
 |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
 +-----+-----+---------+------+---+----++----+---+------+---------+-----+-----+
 | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
 +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+

A quick search on the internet learns that at least for the RPi 3: https://www.raspberrypi.org/forums/viewtopic.php?t=167773

Zitat:
ID_SD and ID_SC PINS:
These pins are reserved for ID EEPROM.
At boot time this I2C interface will be
interrogated to look for an EEPROM
that identifes the attached board and
allows automagic setup of the GPIOs
(and optionally, Linux drivers).
DO NOT USE these pins for anything other
than attaching an I2C ID EEPROM. Leave
unconnected if ID EEPROM not required

In fact ... I was so puzzled by Edwin's answer that I spend a day trying to get both interfaces up, what else is there to do on Sunday. Well, I ended up with a corrupt SD card and a rather time consuming reinstall

Kind regards,

Koen.

i2c multi master

2020-02-27T15:33:43.768000Z

Hi,
you could add two I2C master - start here to read:
https://www.raspberrypi.org/forums/view ... 44&t=88882
so if you have it enabled on Linux just then in CODESYS add the second master and add
the correct I2C file path to the device.

BR
Edwin

i2c multi master

2020-02-27T15:33:43.083000Z

I doubt that you can use a second I2C master since Raspberry Pi only offers one I2C interface, you can however put multiple masters on one I2C interface (i.e. two Raspberry Pi's).

HTH,

Koen.

i2c multi master

2020-02-27T15:33:42.399000Z

Hi, I saw that you can program 2 i2c Master. How can I use them? What are the other pins for controlling the second i2c network?

Thanks in advance for the help

Massimo

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