CODESYS - the IEC 61131-3 automation software

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 Post subject: i2c multi master
PostPosted: Fri Nov 23, 2018 4:03 pm 
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Joined: Wed Mar 28, 2018 3:12 pm
Posts: 14
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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 Post subject: Re: i2c multi master
PostPosted: Fri Nov 23, 2018 6:10 pm 
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Joined: Sat May 23, 2015 1:28 pm
Posts: 11
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.


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 Post subject: Re: i2c multi master
PostPosted: Sun Nov 25, 2018 8:05 am 
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Joined: Mon Sep 05, 2005 9:42 am
Posts: 3018
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


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 Post subject: Re: i2c multi master
PostPosted: Sun Nov 25, 2018 3:20 pm 
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Joined: Sat May 23, 2015 1:28 pm
Posts: 11
Okay ... I stand corrected. :o

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

Kind regards,

Koen.


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