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Felicitus
Joined: 29 Apr 2013, 10:06
Posts: 20
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As Carambola2 lacks I²C support, I'm wondering if some of you already have solved this; for example, via SPI-I²C bridges.
In particular, a device which is already supported by Linux would be very neat. Any ideas?
Thanks
Felicitus
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| 26 May 2013, 15:06 |
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tty
Joined: 18 Mar 2012, 19:06
Posts: 52
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| 27 May 2013, 10:03 |
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Felicitus
Joined: 29 Apr 2013, 10:06
Posts: 20
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That's pretty neat, thank you for sharing! I originally thought that I need a SPI->i²C bridge, but that's elegant, too!
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| 27 May 2013, 10:08 |
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old_europe
Joined: 08 Oct 2013, 18:13
Posts: 5
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| 08 Oct 2013, 19:38 |
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hutorny
Joined: 11 Jun 2013, 11:34
Posts: 39
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| 12 Oct 2013, 15:26 |
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tty
Joined: 18 Mar 2012, 19:06
Posts: 52
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| 12 Oct 2013, 22:04 |
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hutorny
Joined: 11 Jun 2013, 11:34
Posts: 39
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| 13 Oct 2013, 04:51 |
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tty
Joined: 18 Mar 2012, 19:06
Posts: 52
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Because of not true_I2c bus I am afraid there are not open drain pins. Have a look at this:
PU/PD Resistance 200 kOm
Attachments:
gpio_c.png [ 32.41 KiB | Viewed 7856 times ]
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| 13 Oct 2013, 09:47 |
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hutorny
Joined: 11 Jun 2013, 11:34
Posts: 39
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| 13 Oct 2013, 13:03 |
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tty
Joined: 18 Mar 2012, 19:06
Posts: 52
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There is a 2.2K resistor on each I2C line. The lines are effectively pulled up to 3.3V, resulting in approximately 1.5 mA of pull-up current.
A good rule of thumb is that if a downstream I2C device can sink more than 5 mA of current, the protocol should operate properly. I think there is no problem to stretch SCL, you can try it.
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| 13 Oct 2013, 16:25 |
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