From: Neil Cobbett <nco@ba...> - 2007-10-25 17:17:05
Does anyone know how to change the default speed of the Gumstix I2C bus
from 400KHz down to 100KHz. i.e down form its normal fast mode to the
slower standard mode?
From the I2C spec. It implies that all devices will work at the lower
speed. However IF the master is running at 400KHz and you have a slow
100KHZ slave on the bus (that isnt capable of 400KHz) then you can't
communicate with it.
I have one such device and need to change the speed of the Master
(Gumstix) to 100KHz.
I have checked over the wiki and the only info I can get is:
* The I2C unit supports a fast mode operation of 400 Kbits/sec and a
standard mode of 100 Kbits/sec. Refer to I2C bus specification
Note the I2C on the Gumstix
Not much help! Any one come across how to do this?
This message (and any attachments) is for the recipient only. NERC is subject
to the Freedom of Information Act 2000 and the contents of this email and any
reply you make may be disclosed by NERC unless it is exempt from release under
the Act. Any material supplied to NERC may be stored in an electronic
records management system.
From: Dave Hylands <dhylands@gm...> - 2007-10-25 18:07:24
On 10/25/07, Neil Cobbett <nco@...> wrote:
> Does anyone know how to change the default speed of the Gumstix I2C bus
> from 400KHz down to 100KHz. i.e down form its normal fast mode to the
> slower standard mode?
I believe that the default speed is 100 kHz. In fact, the i2c-pxa.c
(or pxa-regs.h) file doesn't even have a definition for the Fast Mode
bit (bit 15 of the ICR register).
Vancouver, BC, Canada
Get latest updates about Open Source Projects, Conferences and News.