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CRTouch Reset to Active Delay

Question asked by Ashley Clarke on May 11, 2018
Latest reply on May 16, 2018 by Jose Alberto Reyes Morales

I have a CRTouch attached to a Vybrid CPU (running MQX) and a Resistive Touch Screen communicating using I2C.   The datasheet quotes the reset to run period as being a maximum of 13mS (A.7 P61).   I have discovered that if I try to read back the configuration registers too soon after the reset line goes high I read back what would seem to be incorrect values.   I can only assume the values reported are not the actual register values as the device usually continues to work.   I have found that sometimes I need to extend the post-reset delay beyond 150mS before the configuration registers read back reliably.   I am concerned that either the datasheet is incorrect, we have a hardware issue or possibly faulty chips?   Has anybody experienced similar?   Does anybody from NXP know the answer?   I don't seem to be able to find any good application notes for the CRTouch.   Could this be connected to the state of the comm select pin?  The datasheet is ambiguous.  We have tied it high.  The datasheet says it must be high as the device comes out of reset to select I2C but on the tower board and eval kit it is floating with no jumper option to tie it to VCC.

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