# RCM4010 Discretes on Port A **URL:** \ **Category:** Rabbit\ **Created:** [December 10, 2008, 10:49pm UTC](https://forums.digi.com/t/rcm4010-discretes-on-port-a/9318 "2008-12-10T22:49:07Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![rjboonstra](https://avatars.discourse-cdn.com/v4/letter/r/439d5e/32.png) [@rjboonstra](https://forums.digi.com/u/rjboonstra)\ **Post date:** [December 10, 2008, 10:49pm UTC](https://forums.digi.com/t/rcm4010-discretes-on-port-a/9318/1 "2008-12-10T22:49:07Z")
I have a project which is using a number of discretes inputs / outpus as well as two serial ports. I opted to use Port A for a number of my discrete inputs / outputs, but now have realized that it is not possilbe to use the Dynamic C software to monitor the program via execution as it uses Port A. Is this assumption correct? Also, will there be any issues / interference to the Port A communications (directly on the RCM) with discretes being switched on / off on the parent board? Thanks in advance… Rudy ---
**Author:** ![rjboonstra](https://avatars.discourse-cdn.com/v4/letter/r/439d5e/32.png) [@rjboonstra](https://forums.digi.com/u/rjboonstra)\ **Post date:** [December 12, 2008, 3:09pm UTC](https://forums.digi.com/t/rcm4010-discretes-on-port-a/9318/2 "2008-12-12T15:09:56Z")
Parallel port A is by default, set up as inputs as per chapter 8.2 in the R4000.pdf Core Manual. 8.2.1 I/O Pins Parallel Port A uses pins PA0 through PA7. These pins can be used as follows. � General-purpose 8-bit data input (write 0x080 to SPCR) � General-purpose 8-bit data output (write 0x084 to SPCR) � Slave port data bus (write 0x088 to SPCR) � Data bus of the auxiliary I/O bus (write 0x08C to SPCR) All Parallel Port A bits are inputs at startup or reset. See the associated peripheral chapters for details on how they use Parallel Port A. Programming port A is on PC6 / PC7. An important note is that parallel port A, if used for discrete I/O, must be all input or all output.:rolleyes: