Reuse of P30/31 for programming/general serial
Steve Hicks (N5AC)
Posts: 20
I would like to be able to do a couple of things with a serial port:
1. Interface to a PC to update operating parameters in my Propeller software
2. Reprogram the EEPROM on the propeller with new software from a PC application
My questions are:
1. Can I reuse the "main" serial port (P30/31) to both program the EEPROM attached to the propeller as well as interact with my program? -- I believe this is a "yes," and so I'm trying to understand the DTR/RESn·relationship.· I am guessing that the Propeller tool pulses RESn (via DTR) and then communicates with the chip to reprogram the software.· If this is the case, I assume that my PC program can just interact with the running software provided it doesn't mess with DTR.
2. My PC application is a .NET application that will be periodically updated.· Can I use the application to also update the propeller software via the on-board boot-loader program?· In other words, can I pulse DTR and interact with the boot-loader to rewrite the EEPROM also?· Is there documentation on how to do this?
Thanks,
Steve
1. Interface to a PC to update operating parameters in my Propeller software
2. Reprogram the EEPROM on the propeller with new software from a PC application
My questions are:
1. Can I reuse the "main" serial port (P30/31) to both program the EEPROM attached to the propeller as well as interact with my program? -- I believe this is a "yes," and so I'm trying to understand the DTR/RESn·relationship.· I am guessing that the Propeller tool pulses RESn (via DTR) and then communicates with the chip to reprogram the software.· If this is the case, I assume that my PC program can just interact with the running software provided it doesn't mess with DTR.
2. My PC application is a .NET application that will be periodically updated.· Can I use the application to also update the propeller software via the on-board boot-loader program?· In other words, can I pulse DTR and interact with the boot-loader to rewrite the EEPROM also?· Is there documentation on how to do this?
Thanks,
Steve
Comments
Thanks,
Steve
2) You could write a loader. Chip has posted the protocol and someone else (Paul? Beau?) has talked about writing a PC loader, but hasn't had the time. The EEPROM writer just copies the whole RAM to the whole EEPROM once the RAM is loaded. There's no fine control of EEPROM interaction if that's what you're asking.
If your software is capable of controlling the DTR and forcing it LOW(-V), then you shouldn't have a problem.· On the other hand you could try this circuit modification below to see if it
would work.· It uses the RTS signal rather that the DTR to get a -V reference.· The drawback is that your bringing a 5th·connection from the DB9 Serial connector instead of the 4
connections that are currently being used.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Having one more wire isn't that bad when you consider that now you have a debug port and a programming port all in one.
thanks.