Francisco,
The pins 6 & 7 on the master and slave pins 2 & 7 were used for the PICAXE programming header. The current circuit boards were designed when we were using the picaxe chips, but now that we have moved from the picaxe to bare chips and pbp the PICAXE headers are no longer needed. Peter has found a use for the picaxe programming lead on the master by using it to supply data, but unless you need it you can leave these components off of the pcb. What is required for the next version of the boards, both slave and master, is a ICSP header to replace the PICAXE header, so the pics can be programmed on the board. At the moment you have to remove them for programming. The pinout for the slaves at present is
Code: Select all
'************************** Slave PIC12F683 Pinouts ****************************
' Top
' _____
'(+ Cell Supply) +Ve -1| ^ |8- -Ve (- Cell Supply)
'(Slave Alive Out) GP5 -2| 6 |7- GP0 (Bypass Load Out)
'(Slave Data Bus Out) GP4 -3| 8 |6- GP1 (RefAdc In 1.235V)
'(Slave Data Bus In) GP3 -4| 3 |5- GP2 (Master Data Bus Out)
' -----
So pin 2 now toggles high/low but is not connected to anything. This is just a diagnostic aid, by connecting an oscilloscope to the pin you can check the slave is alive. Pin 7 is and has always been connected to the bypass load as well as the programming header. When programming the pic with the picaxe lead it toggled the load as well but that never affected the programming so it didn't matter. You will find a similar section in the master code, so I won't re-post it here. If you have designed, or are designing new boards, please post some pictures of your work for the benefit of us and others.
Pin 17 and 18 are indeed the hardware UART ports for the 16F886, but again because the board was designed for the PICAXE we have not necessarily used these pins for RX and TX. For version 3 these will be used for communications, but they have yet to be built. One thing I have found out is that it is possible to connect a pic to a serial port with just a 22k resistor from the TX on the pc to the RX on the pic and a current limiting resistor (470 to 1k) on the pc RX and the pic TX. The 22k resistor limits the current from the +10 to -10 volts RS232 levels to a safe amount for the pic and most PCs have no problem receiving TTL serial data. So while it doesn't comply with the RS232 standard it is good enough. 2 points to watch out for is that you have to use inverted serial on the pic and because of that you need to use the SERIN or SERIN2 command and not HSERIN. The thing that strikes me about this is that is what the picaxe programming header basically looks like, so it seems that is what they have been doing as well. Hope that helps.