[OpenWrt-Devel] Is "using gpio to simulate I2C bus" robust on AR9331?

[Gareth Parker]

OpenWrt seems dead these days, active development is over at lede-project.

Also for i2c I would recommend using a PIC microcontroller, its far easier and designed for that purpose.  I use a PIC to control PLL IC's over i2c such as the TSA5511 in FM broadcast gear I design.

Gareth

-----Original Message-----
From: openwrt-devel [mailto:openwrt-devel-bounces at lists.openwrt.org] On Behalf Of Hartmut Knaack
Sent: Friday, 5 May 2017 9:19 a.m.
To: Xuebing Wang; OpenWrt Development List
Cc: John Crispin
Subject: Re: [OpenWrt-Devel] Is "using gpio to simulate I2C bus" robust on AR9331?

Xuebing Wang schrieb am 04.05.2017 um 03:19:
> Hi community,
> 
> I am using Atheros AR9331 + OpenWRT Chaos Calmer 15.05 on a commercial 
> product.
> 
> I've used I2C on many projects, all with dedicated I2C controllers. 
> I've never used GPIOs to simulate I2C on Linux.
> 
> I may be wrong, I am tending to think that there is no way to generate 
> good I2C waveforms by using 2 GPIOs (SCL/SDA), except that we disable 
> all interrupts and maybe using high precision timer when outputing SCL/SDA?
> 
> Is "using gpio to simulate I2C bus" robust on AR9331?
> 

I have been using a GPIO extender connected via I2C to a router powered by an AR9132 (should be close enough), running for months without notable issues.
In that case, I2C traffic was pretty low, it just had to access the GPIOs of the extender a couple of times per hour. It has been way better than using an I2C-Tiny USB adapter, but that would be a different story.

> Thanks.
> Xuebing Wang
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