MCA backend won't boot

[Go4IT]

Hey folks, these days i got an non-starting MCA unit. It is the backend that has failed, the frontend is ok.
The untit draw about 110 mA at 12 V.

Even if RAMs are from week 44/2010 i've heated them up to see if they react, but no success.
Next i measured all the voltages and they are ok. I've reflashed the unit, once with an known running firmware and once with the same. Both could be programmed without a problem, so at least CPU and Flash seem ok.

At least i've swapped the Radio-Processor (V850, uPD70F3283) with a working MCA and can tell it's also not the problem. But the bad unit won't boot.

Now i'm, getting a little out of ideas... i once got a similar problem with an NX unit (see viewtopic.php?t=249) and couldn't solve this either.

If i only could get some debug messages out, why the firmware don't boot up.

[Go4IT]

I now again digged very deep into the system to find the cause of that error. As said, i can connect via JTAG to the OMAP and it looks like OMAP behaving fine, but when i halt the CPU and show the registers i see that it always get stuck in an ABORT at PC 0xFFFF000C, which is also the reset-vector of ABORT mode:

Code: Select all

J-Link: ARM9 CP15 Settings changed: 5327F from 78, MMU On, ICache On, DCache On
PC: (R15) = FFFF000C, CPSR = 000000D7 (ABORT mode, ARM FIQ dis. IRQ dis.)
Current:
     R0 =00000003, R1 =9014D818, R2 =2C28D86C, R3 =00070F7C
     R4 =90000014, R5 =2000FE28, R6 =00000000, R7 =0000001C
     R8 =00000040, R9 =FFF6FACD, R10=3BFF97FE, R11=00040034, R12=00000000
     R13=BBE9D6AB, R14=00000002, SPSR=000000F7
USR: R8 =00000040, R9 =FFF6FACD, R10=3BFF97FE, R11=00040034, R12=00000000
     R13=4BDFFB35, R14=FE7B70FF
FIQ: R8 =F819FD75, R9 =EBCD07F7, R10=F9DFA3D6, R11=F7FFAFF7, R12=CE7FBED9
     R13=F3FBFD73, R14=67EEFFF1, SPSR=00000010
IRQ: R13=FEBED7DA, R14=F46E7BFE, SPSR=00000010
SVC: R13=2000FE18, R14=00001FA0, SPSR=00000010
ABT: R13=BBE9D6AB, R14=00000002, SPSR=000000F7
UND: R13=9FF77F7B, R14=BF7DFFD1, SPSR=00000010

Connecting was easy using the Segger J-Link. Only keep in mind to prevent V850 to do watchdog-resets by pulling it's reset-line down (Tuareg mode) and once connected using J-Link (ARM9, LittleEndian, rest is default), also disable the OMAP watchdogs using:

Code: Select all

connect
halt
write4 0xFFFEC808 0xF5
write4 0xFFFEC808 0xA0
write4 0xFFFEB048 0xAAAA
write4 0xFFFEB048 0x5555

After that you can also single-step, set breakpoints, etc. and have all the time in the world to look at the results in memory or registers.