SLUG seems to be dead after RAM upgrade
after fattening the slug with 2 pieces of Micron MT48LC32M16A2
512Mbit SDRAM to 128MByte by replacing the original chips, my device
doesn't boot anymore. All four LEDs are dark, and on the serial
console I don't see anything, even the really first + sign from
redBoot. Via JTAG I'm able to read the flash memory, and I can see
there is flash content mapped also to the address from 0x00000000, so
it seems MEM_MAP flag in EXP_CNFG0 register still have the original
I used hot air rework station and ESD protection to remove the
original RAM chips. I soldered the new RAMs in under microscope,
everything looks fine visually.
Please answer my questions, and give me some additional hints how to
continue the debug process.
Q1: Does redBoot have any activity on the uart if there are no SDRAMs,
or they are corrupted, etc...?
Q2: Could it be possible to kill the PCB (e.g. killing some embedded
via, etc...) by hot air?
Q3: What is the exact location of the 4 resistors under the buzzer?
I've blown them off with the hot air, and I don't know where to solder
them back. I haven't found any picture with desoldered buzzer in the
necessary resolution to identify the 4 resistors (822, 123, and
2*103). However I think these are necessary only for the buzzer
functionality, but who knows? (I've tried to figure out the
configuration of them from the LM358's datasheet)
Q4: Should peek, poke and readmem JTAG commands work properly also
with registers? I was able to read out only crazy values e.g.: from
EXP_CNFG0 or SDR_CONFIG.
Q5: Is there any way to follow the boot sequence via JTAG? (I don't
have any expensive debugger, only the free JTAG Tools 0.5.1.)
Thanks in advance,