CRTouch Reset to Active Delay

[ashbc1]

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.

[reyes]

Hi,

COMMSEL is connected to ground only if UART communication is desired. Otherwise it can be left unconnected.

Regarding the 13ms, take in mind that this time is only valid for power on reset, pin reset and shutdown wakeup. And this timing can only happen if the voltage levels on VDD.

regards,

Jose