From: Peter B. <pet...@cs...> - 2007-02-26 18:34:18
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Hey there, Been trying to connect a Capacitive Sensor Board (AD7746) [1] via the breakout-gs using i2c to the gumstix platform with little success. When I run the i2c programme to read from the sensor I get the following error: #i2c 0x72 rb 0x00 i2c: error: exhausted retries i2c: msg_num: 0 msg_idx: -2000 msg_ptr: 0 i2c: ICR: 000007e0 ISR: 00000002 i2c: log: [00000446:000007e0] ERROR: I2cTransfer: ioctl failed: Remote I/O error (121) ERROR: I2cReadByte failed: -1 I'm using a recent build (1238) with both the i2c-dev and i2c-pxa modules included. I've also attached pull-up resistors (4.7k ohms) to SDA and SCL lines and have connected up ground. The basic hardware set up is as follows: connex-400xm with a wifistix and breakout-gs board attached. The AD7746 is connect via the i2c pins on the breakout-gs board. As far as I'm aware the AD7746 is compatible with the 3.3V that the breakout-gs board provides. Also, I should say that when I attach an oscilloscope to SDA or SCL that I can see the signals from the above i2c command. Am I missing something here? Is the AD7746 actually compatible with the i2c implementation on the gumstix. If anyone has any experience with the above hardware I be gratefully for any insight you may be able to provide. Regards, Pete [1] http://www.sparkfun.com/commerce/product_info.php?products_id=7918 |
From: Dave H. <dhy...@gm...> - 2007-02-26 18:42:43
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Hi Peter, > Been trying to connect a Capacitive Sensor Board (AD7746) [1] via the > breakout-gs using i2c to the gumstix platform with little success. When > I run the i2c programme to read from the sensor I get the following > error: > > #i2c 0x72 rb 0x00 I think you meant to use decimal 72, not hexadecimal 72. According to the data sheet, it uses a "byte address" of 0x90 for reads and 0x91 for writes. What this really means is that it uses a 7-bit address of 0x48 0x48 = 72 -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Peter B. <pet...@cs...> - 2007-02-27 10:39:53
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Yep, that worked. A silly mistake. Thanks Dave for pointing it out to me. pete On Mon, 2007-02-26 at 10:42 -0800, Dave Hylands wrote: > Hi Peter, > > > Been trying to connect a Capacitive Sensor Board (AD7746) [1] via the > > breakout-gs using i2c to the gumstix platform with little success. When > > I run the i2c programme to read from the sensor I get the following > > error: > > > > #i2c 0x72 rb 0x00 > > I think you meant to use decimal 72, not hexadecimal 72. > > According to the data sheet, it uses a "byte address" of 0x90 for > reads and 0x91 for writes. What this really means is that it uses a > 7-bit address of 0x48 > > 0x48 = 72 > |