Thread: Producing Qwerty OtherHalf --order counter: 75/75 --ordering closed
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mikecomputing is offline mikecomputing
2013-10-13 , 10:38
Posts: 3,464 | Thanked: 5,107 times | Joined on Feb 2010 @ Gothenburg in Sweden
#108
Originally Posted by dirkvl View Post
Edit: the more I learn about this whole I2C, the more I come to realize they MUST include an interrupt line. Polling for every single OH would make it useless. Polling for OH with camera shutter? Forget it! If the TCA8424 works with MER and de Mallit-keyboard, I say we go for it!
No need for IRQ for this kind of peripheral better let OH be master. See my post below.


Originally Posted by jalyst View Post
What are the downsides/upsides to this approach versus other one?
not an expert only has used it on low end embedded but i2c allow more than one device to be master. Not sure what is best except the later save one pin...

Most the time "mainboard CPU" (means Phone SoC in this case) is master.

But if no IRQ the solution would be to set the OH as master when line is idle and it want to send data and when OH has pulses the adress the SoC on phone would get interrupt as a slave.

But question still remains how Jolla has implemented the I2C kerneldriver and so on.

hmm when thinking of it there should not be a reason for SoC to be master in this case. Better let the OH be master...

But it would be another way around if connected for example an eeprom module or similar...
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Last edited by mikecomputing; 2013-10-13 at 10:41.
 

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