AT91SAM7S and SAM-BA

ATMEL in-system programing solution including SAM-BA and SAM-PROG.

Moderators: nferre, fab

jal
Posts: 3
Joined: Sun Aug 03, 2014 3:55 pm

AT91SAM7S and SAM-BA

Sun Aug 03, 2014 4:33 pm

Working with a custom design PCB based on AT91SAM7S256 part.   I'm trying to program boards using SAM-BA v2.6 (also tried v2.12 with patch 7).   My setup is as follows...

a)  Power supply to the board (verified voltages are good)
b)  Laptop-> USB to Serial cable -> BB Electronics RS232 to TTL level converter -> PA9,10 on the target
c)   I have a jumper for the TST pin which drives TST high when jumper is installed.

So far I have been unable to get a target connection using either version.    On V2.6 I get an error message about failing to read the board ID,   on V2.12 I get an error saying communications failure.

I've traced the TTL signals going into the board and they look like decent levels.   I see the following activity...
PC sends the following sequence 0x80,0x80, 0x23 '#','N#', <approx 1 sec delay>,  then "wFFFFEE40,4#".

At no time do I see any response from the target.   The commands being send sort of make sense in terms of the SAM-BA section of the AT91SAM7 manual except that I do not see a documentation for the "N#" command.

Other hardware stuff...
- When using the TST operation I've verified that PA0,1,2 are all pulled high.   This should invoke the boot recovery operation?
- I've checked to make sure that the PLLRC has an external filter ( one web posting mentioned that this was necessary)

Anyone have any tips on what could go going wrong???

Thanks
Jim
jharley
Posts: 238
Joined: Thu Dec 06, 2012 6:40 am

Re: AT91SAM7S and SAM-BA

Sun Aug 03, 2014 6:25 pm

jal wrote:b) Laptop-> USB to Serial cable -> BB Electronics RS232 to TTL level converter -> PA9,10 on the target
How is this connected? It should be:
TTL (TD) <--> SAM7S (DRXD, PA9)
TTL (RD) <--> SAM7S (DTXD, PA10)
jal wrote:- When using the TST operation I've verified that PA0,1,2 are all pulled high. This should invoke the boot recovery operation?
Specifically the sequence is:
1) power off
2) strap TST, PA0, PA1, PA2 high
3) power on for 10 seconds
4) power off
5) remove strap for TST, PA0, PA1, PA2
6) power on
7) Connect SAM-BA
jal
Posts: 3
Joined: Sun Aug 03, 2014 3:55 pm

Re: AT91SAM7S and SAM-BA

Sun Aug 03, 2014 7:12 pm

Thank-you for your replay.

I have the connection setup according to the signal assignments that you listed.

I also followed the procedure as you've outlined for restoring the boot code.    No Joy!

This board is configured with a 18.432MHz crystal.   When probing the crystal pads I see no detectable oscillation at either pin so unless the AT91SAM7 automatically runs from an internal osc.  this would be a problem too.

I will try adding some loading capacitance to see if the crystal will show me a real signal.

Regards,
Jim
jal
Posts: 3
Joined: Sun Aug 03, 2014 3:55 pm

Re: AT91SAM7S and SAM-BA

Wed Aug 06, 2014 6:50 pm

Crystal issue turns out to be a red herring.   Even on known good boards cannot see much of an oscillation w/ my 20MHz scope.

Double/triple checked all the wiring,   tried multiple target boards,  a "real" com port vs USB->Serial adapter,   different RS232/TTL converters.    All get the same results ..

a) See SAM-BA sending data to the AT91SAM7 but nothing coming back.
b) Still wondering about SAM-BA sending an "N#" command?   This is not one of the documented commands for this part.

Is there some timing issue with when to power up/reset the board vs. starting SAM-BA connection?   

Running out of ideas on this one.....can it really be this hard to reflash a micro?

Thanks
Jim

Return to “AT91-ISP”

Who is online

Users browsing this forum: No registered users and 1 guest