I am creating a GPIO board for my home automation. Of course it can be also used to do other things
I have already created one, but found some trouble on it, so I am designing a second one.
Here is the schematic I have already done :
The board has :
64 digital IOs, each 8 pairs of IO are set either in input or output at 5V level
1 RS232 serial port
1 UART port (3.3V signal level)
1 GSM module
2 I2C port (5V level)
The issue I have is for the level converter on the GSM modem. I am not sure that it is correct like that (See U18 and U19).
If somebody can check and let me know if this schematic is ok, the more eyes are looking, the less error it has