Hi all
I have two batch of boards with TMS320CV5509A dsps. The first batch is
programming fine using JTAG and I can run the program just using JTAG
(without external memory). In the second batch revision, for some
reason i cannot get the Jtag to get working. It comes up with POWER
Failure error as if it is having problem detecting power on the PCB. I
have checked the PD line and it is getting power fine at 3.3V, but the
TRST is at 1.6V rather than 3.3. THen I plugged in the first board that
is working fine with jtag and on it the trst and PD both were 3.3V. I
just cant understand what may be going wrong as both boards are
supposed to be exactly the same. Only difference are following
1. in second board the switching regulator is replaced with lenear
regulator
2. the length of wire between JTAG and board is now about 12inch rather
than 6 inches previously
please help
jtag trst voltage level
Started by ●June 11, 2008
Reply by ●June 11, 20082008-06-11
Taimurk-
> I have two batch of boards with TMS320CV5509A dsps. The first batch is
> programming fine using JTAG and I can run the program just using JTAG
> (without external memory). In the second batch revision, for some
> reason i cannot get the Jtag to get working. It comes up with POWER
> Failure error as if it is having problem detecting power on the PCB. I
> have checked the PD line and it is getting power fine at 3.3V, but the
> TRST is at 1.6V rather than 3.3. THen I plugged in the first board that
> is working fine with jtag and on it the trst and PD both were 3.3V. I
> just cant understand what may be going wrong as both boards are
> supposed to be exactly the same. Only difference are following
> 1. in second board the switching regulator is replaced with lenear
> regulator
> 2. the length of wire between JTAG and board is now about 12inch rather
> than 6 inches previously
If the second board uses switching power instead of an LVR, then obviously you are
faced with design differences, not "batch" differences. Maybe your manager is
telling you "batch" so he thinks it's easy -- just compare the boards, right -- and
you should solve this quickly, but if so then you need to set him straight.
One guess is that in the second board you either don't have a pull-down R on TRST or
the value is different. But really it could be a lot of things; i.e. something may
be fundamentally different.
You need to compare the two (2) schematics carefully, in detail. Also on the 2nd
board, compare the BOM with the actual board values, one-by-one.
-Jeff
> I have two batch of boards with TMS320CV5509A dsps. The first batch is
> programming fine using JTAG and I can run the program just using JTAG
> (without external memory). In the second batch revision, for some
> reason i cannot get the Jtag to get working. It comes up with POWER
> Failure error as if it is having problem detecting power on the PCB. I
> have checked the PD line and it is getting power fine at 3.3V, but the
> TRST is at 1.6V rather than 3.3. THen I plugged in the first board that
> is working fine with jtag and on it the trst and PD both were 3.3V. I
> just cant understand what may be going wrong as both boards are
> supposed to be exactly the same. Only difference are following
> 1. in second board the switching regulator is replaced with lenear
> regulator
> 2. the length of wire between JTAG and board is now about 12inch rather
> than 6 inches previously
If the second board uses switching power instead of an LVR, then obviously you are
faced with design differences, not "batch" differences. Maybe your manager is
telling you "batch" so he thinks it's easy -- just compare the boards, right -- and
you should solve this quickly, but if so then you need to set him straight.
One guess is that in the second board you either don't have a pull-down R on TRST or
the value is different. But really it could be a lot of things; i.e. something may
be fundamentally different.
You need to compare the two (2) schematics carefully, in detail. Also on the 2nd
board, compare the BOM with the actual board values, one-by-one.
-Jeff
Reply by ●June 11, 20082008-06-11
