many o pic's o where thou go ?

[Guest]

Hello,

guess you got to interconnent 17 PIC18F44XX.

One of these, it connectes to RS232,
You need to update all o these over the serial line, tell me about
possible conns, the other 16 are connected to the first PIC.
It's got to work all the time.
Faulty action means -$$$.

Yes, I'll use 17 Pic's in my project.
Ill try hard workin' out the bootloader + encryption (if someone makes things clear how I can Protect my stuff with it).

So, what type of interface, daisy chain,, .. / ??
It's 18 F XXXX

Thanks Martin

[asmallri]

I do something very similar with serial, SPI and Ethernet implementations.

For the serial implementation, the primary PIC has a RS232 interface which is used for the bootloader. All other PICs are connected to the primary PIC over a RS485 bus. My application is a distributed data acquisition system with the RS485 bus being used for data and bootloading. The bootloader on the primary PIC has a "transparent mode". When the primary is in bootloader mode, I can sent it a bootloader command to go into "transparent mode" in which case it will echo all data transparently between the RS232 and RS485 busses. Each device on the RS485 bus is addressable. I send a command to the specific PIC I want to bootload to cause it to reset (my bootloaders are only active within the first few seconds of reset). Once the target PIC is reset I "capture" it with the bootloader and then load new code to the target PIC. When I have finished bootloading the slave PIC I "release" the slave and it reboots. When I have finished bootloading the slaves, the master pic is taken out of transparent mode and reset.

I have used similar mechanisms for bootloading over SPI and Ethernet. In one case I used RS232 to the Primary PIC, RS485 to the first tier of multiple slave PICs and SPI between the slave PICs and MAXIM 1463 MPU based A/D subsystem.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

[Guest]

Please, asmallri,

is it a mistery at all,
I do't think so.
Why (how) use encryption ????????????????

Thanks Martin

[SherpaDoug]

How far are the slave PICs from the master? If it is less than a couple of meters I would use SPI to connect the PICs together. If data errors would be catastrophic add checksums to the data messages.
Do you really need a bootloader? Security is simpler without one.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[MikeValencia]

To interconnect all those PICs together, wouldn't CAN be one of the top candidates?