Programming 16f877a on the air

[umutso]

Hello all

I have a circuit with 16f877a integrated with a gprs modüle. Gprs modüle registers to my server on a certain port via tcp stack. Pic gets values and sends via GPRS network to my server. All fine. But I need to update my code on the chip sometimes. The chip has serial boot loader and it works wired. But don't know how to send new hex file over this GPRS network.

If you can help me on this it will be great.

Thanks in advance
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Umut Sonkurt

[Gabriel]

Send the hexfile (after all, its just a collection of bytes) and save that to a local eeprom on the pic... have the bootloader load file saved in eeprom...

Make sure to include a checksum or something so that the bootloader only updates the code once its sure its got the correct and complete update file.



G.
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CCS PCM 5.078 & CCS PCH 5.093

[umutso]

Thanks for your reply. Do you have a template or sample code to do so that I search the net but no luck. I m using ccs compiler.

Thanks
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Umut Sonkurt

[Gabriel]

No, I dont, and i dont think anyone else here does for that matter...

but maybe if you posted some information or code others could join in and try to help or give you suggestions, reference a good application note or something...

details like what bootloader are you using? where did you get it? is it ccs provided? is it by other known parties? can you post the bootloading code?

can you send data to the pic via GPRS? even a single byte? how?
do you have local storage on your pic board to buffer the incomming update hex file?

alot of things have to work right for your project to go right.


also, My personal opinion when i read:

[umutso]

I'm using boot loader program from microchip site. With pic boot loader sw from same site I can serially update my program on the pic.

I can also send and receive simple text strings via GPRS connection to a tcp listener over a socket connection.

Just can not send a program data via same GPRS connection to update the program in the pic. On this topic that's why I need help since I really do not know how to or where to start.

People are saying on the net upload your program to the internal EPROM and then load it to flash to use. That's it. I need a start point at least.

Thanks
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Umut Sonkurt

[Gabriel]

As a Starting point you should:

Locally, in your lab, load a HEX file to EEPROM.
Modify your bootloader to program the pic from EEPROM instead of UART serial data...
get it to work...

you should probably post your:

CCS Version
EEPROM chip#
PIC #
Post your Bootloader code (the one on the PIC) (preferably in CCS)


Make a _small_ test program that receives serial data and stores it to EEPROM... and then tries to flash the pic with the data on the EEPROM.


Post that on this forum... plenty more people will help you.




does your _remote_ board have onboard EEPROM? if it does not, its going to be alot harder...can you modify/add memory to your remote board?



G.
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CCS PCM 5.078 & CCS PCH 5.093

[umutso]

Hi Gabriel,

I m using 16F877A which has a 256 bytes of internal eprom.So I m planning to use this area instead of an external one. I will also port the bootloader code in a few minutes.
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Umut Sonkurt

[Gabriel]

[FvM]

For a fail-safe remote update, the complete binary image must stored in an intermediate storage. The on-chip EEPROM is surely not sufficient for this purpose.

Alternatively, the GPRS modem control must be implemented in the bootloader, too. Usually, the memory size available for the bootloader won't allow it.

[umutso]

Let me explain;

the GPRS board is a seperate secondary board which can operate seperately and manageed also seperately. My 16F877A only sleeps and awakens certain time periods and contacting a 5V relay which Powers up the GPRS modem and the modem connects opens the socket to the TCP server seperately. WHen it connects my 16F877A awaits the connected state and when got, it triggers my sensor and gets the result of the measurement andsends the result via UART via MAX232 to the gprs modem so to the tcp server accross.

So my controller only ;

sleep
awaken
contact the 5V relay to power up the modem
waits for the connect state
triggers the sensor
gets the result
sends the result to UART
Sleep again

thats it. So there is no GPRS ommunication codes or plenty of codes inside since GPRS modem is a seperate board.

Thats why I intend to use the internal eeprom on my chip so that I can update just a very tiny code sometime in the controller. Actually I only need to change the sleep and awake timing delays thats it.

Do I have to put an external storage still?
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Umut Sonkurt

[jeremiah]

Rather than try and store the whole code and reprogram it, why not simply have a program send over new sleep and awake timing delays and store those to the EEPROM, then have your code adapt based on those values? I think that will be easier in the long run and less risk for your project.

[umutso]

Hello

this is actually a very nice idea. But I need a sample how can I do this and change. If you can provide me a very simple example code I can start and try it.

Thanks in advance,
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Umut Sonkurt

[Gabriel]

That my friend, is a and ENTIRELY different story.


you need to update a single parameter...
how do you control the sleep period?



G.
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CCS PCM 5.078 & CCS PCH 5.093

[umutso]

I m using DS1302 real time clock. With RTC function every 4 hours, I get my tmr1 int and awake the system, do the job an sleep again t the next 4 hours.
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Umut Sonkurt

[Gabriel]

ok...

so your TMR1 triggers, your pic wakes, you get time from your RTC, check current time agains the "alarm Time" if it matches, you execute the sensor code, else you sleep again... right?

you only need to update your "alarm time" via GPRS...

if the Alarm time is a constant, save it instead in eeprom and update this value only...
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CCS PCM 5.078 & CCS PCH 5.093