Port pin P3.6 is connected to both switch S3 and rx data for Com1. Also, no UART alternate functions are listed in the STR91xF datasheet for P3.6. Is this correct? I have one of these boards on order and I'm planning to connect some additional prototype circuitry to it. Thanks Dave
I have one of these boards sitting in front of me and I can tell you that yes P3.6 is connected to both S3 and to pin 12 of the 232 translator.
You are right, this was a mistake in version 2 of the MCBSTR9 PCB. Unfortunately, the COM1 interface cannot be used on this board because of this (see also http://www.keil.com/support/docs/3211.htm). A few days ago we started to ship version 3 boards. The version 3 schematics will soon be published at http://www.keil.com/mcbstr9/ The differences between version 2 and version 3 are: - COM1 is now connected to P3.0 and P3.1 instead of P3.6 and P3.7. - P3.6 is now only connected to pushbutton S3. - P3.7 is now only connected to jumper J3