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Arcnet
23 Posts |
 Posted - 03 Aug 2003 : 04:43:41
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Hello everybody,
We work with BitsyX Development System.
How can we connect to it periferal device with I2C bus
(chip Phillips SA-7113)?
It's written in manual that I2C connectors are some pins on J3,
but this connector closed on Development Board.
Thanks in advance. |
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akidder
1519 Posts |
Posted - 02 Mar 2004 : 16:21:07
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| Thanks for your post. Take a look at forum topic 1402 for sample code and information about using I2C with Windows CE on the BitsyX. For I2C on the BitsyX, we use the XScale controller instead of the ADSmartIO. |
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sdsteam
60 Posts |
Posted - 13 Mar 2004 : 00:59:18
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We have 6 BitsyX RevC Board, we have peculiar problem with I2C and SMBus, randomly we have read/write failure with error code value 121.
Our application, uses I2C Protocol for RTC and EEPROM Access and also uses SMBus access for Battery and another SMBus Device. ADSmartIO is being used for LCD Brightness Control.
Can there be any conflict between I2C and SmBus as mentioned in User Manual (SMBus Section) ?
Any H/W or S/W Configuration Settings to be done in BitsyX? |
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sdsteam
60 Posts |
Posted - 13 May 2004 : 01:59:15
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| Is it possible to operate the PXA I2C Interface less than 100KHz? |
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akidder
1519 Posts |
Posted - 13 May 2004 : 09:19:47
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The PXA255 I2C bus runs at either 100 or 400 kHz. The baud rate is set with a single bit in one of the XScale registers, so there isn't any baud rate control available.
If your application has a requirement for a slower I2C baud rate, contact us with details.
Cheers, Drew
"There's always a better solution than the one you tried before that didn't work." -H. Jackins
p.s. I've added "and PXA255" to the topic title so it reflects this thread more accurately. |
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sdsteam
60 Posts |
Posted - 21 Jun 2004 : 00:25:19
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More Observation on I2C., We enabled Debug Switch in I2C Driver and Found that the SDA line is pulled low permanently by one of the four devices (RTC,EEPROM,BATTERY(BQ2040),LTC6904) randomly, this basically happens after retry for transmision for 2 times
In General Wrote Bytes Fails Saying -2000/2 bytes wrote......(expected and ret written length is different)
Find below some sample observation..
i2c_pxa_do_xfer Addr: 50
i2c_pxa_do_xfer wrote 2 Bytes
i2c_pxa_do_xfer Addr: 50
i2c_pxa_do_xfer read 2000 Bytes
IBMR: 0
ISR: 5
i2c_pxa_do_xfer Addr: 17
i2c_pxa_do_xfer wrote -2000/2 Bytes
Retry Transmission
i2c_pxa_do_xfer Addr: 17
Retry Transmission
i2c_pxa_do_xfer Addr: 17
Retried 2 Times....
IBMR: 2 (SDA is pulled low permanently...)
Why this happens????? Is there any bug in i2c driver???
Or this behaviour is due to more noise or improper voltage level or pull up resistor???
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akidder
1519 Posts |
Posted - 21 Jun 2004 : 12:36:34
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Thanks for the details. Since our products work consistently with the real-time clock and voltage scaling circuit on the BitsyX, we're fairly certain the driver is ok. Of course, reading the RTC is undoubtedly much less demanding than regularly accessing the types of I2C devices you are using.
Here are a few troubleshooting suggestions, in order of what I think would be easiest to start with :
- Make sure the hardware is current, especially the pull-up resistors. For the BitsyX, see topic 884.
- Insert small resistors (5-100 ohm) in series with each of your devices. This will tell you which device is holding the bus low (by the direction of current flow). You can start by probing the resistors already installed on the BitsyX; this will allow you to determine if the bus is being held low by one of the devices on our board or problem is occuring with one of the ones on your side.
- Try removing individual devices from the I2C bus, adding them back one at a time until all are working.
- Alternatively, try removing individual drivers from your application/build.
I recognize that this process of elimination in these suggestions can be tedious, but it's probably the best way to identify the source of the problem that you are experiencing.
Let us know what you find, either on the forums or directly! Cheers, Drew |
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