Proxmark

Upgrading ELECHOUSE Proxmark3 Easy V3 to 512k

(de)soldering

The popular Proxmark3 Easy has an at91sam7s256 with only 256k and e.g. it's already about 83% full with the current iceman firmware.
So I decided to attempt an upgrade.

at91sam7s512 is about [15€ on http://fr.farnell.com/atmel/at91sam7s512b-au/micro-32-bits-arm7-512k-flash/dp/1972051 Farnell].

The steps I followed to desolder and solder the new chip are basically the same as seen on this youtube video:

• heating the chip with my desoldering station
• removing the chip with a small suction pen
• putting flux on the pads
• cleaning the pads with desoldering wire
• putting the new chip and soldering some pins to lock it in place (look for aligning the small dot on the correct corner)
• putting flux on the pins
• putting solder on the pins, don't be afraid of bridges...
• removing extra solder with desoldering wire
• checking carefully for residual solder bridges

And voila.

Note that it's maybe easier to solder the new chip not by using flux+solder+iron but solder flux paste and heating with air gun, as shown in this video...

JTAG programming

Then wire your JTAG programmer to the board. Mine is a Segger J-Link.
To make it easier, solder a breakable single-row male curved header.
Choose a curved one so you can leave it in place later and still stack the PM3 daughterboard.

Then using Dupont wires male-female, wire it to the JTAG programmer.

For the J-Link, the pinout is:

  ---------  ---------
 |1917151311 9 7 5 3 1|
 |201816141210 8 6 4 2|
  --------------------

PM3  JLink
---  -----
TMS   7
TDI   5
TDO  13
TCK   9
GND   6
3.3  not connected

I didn't connect the 3v3 because J-Link Vref is 5v so I prefered to power the PM3 over USB while reprogramming it.

To use the J-Link on Debian:

$ apt-get install openocd

There is some doc installed locally: file:///usr/share/doc/openocd/openocd.html/index.html

Create /etc/udev/rules.d/60-jlink.rules with

ATTRS{idVendor}=="1366", ATTRS{idProduct}=="0101", MODE="664", GROUP="plugdev"

I created a config file by reusing most of tools/at91sam7s512-buspirate.cfg, but specific to J-Link instead of buspirate:

telnet_port 4444
gdb_port 3333
interface jlink
transport select jtag
adapter_khz 1000
reset_config srst_only srst_pulls_trst
jtag newtap sam7x cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id 0x3f0f0f0f
target create sam7x.cpu arm7tdmi -endian little -chain-position sam7x.cpu
sam7x.cpu configure -event reset-init {
	soft_reset_halt
	mww 0xfffffd00 0xa5000004	# RSTC_CR: Reset peripherals
	mww 0xfffffd44 0x00008000	# WDT_MR: disable watchdog
	mww 0xfffffd08 0xa5000001	# RSTC_MR enable user reset
	mww 0xfffffc20 0x00005001	# CKGR_MOR : enable the main oscillator
	sleep 10
	mww 0xfffffc2c 0x000b1c02	# CKGR_PLLR: 16MHz * 12/2 = 96MHz
	sleep 10
	mww 0xfffffc30 0x00000007	# PMC_MCKR : MCK = PLL / 2 = 48 MHz
	sleep 10
	mww 0xffffff60 0x00480100	# MC_FMR: flash mode (FWS=1,FMCN=72)
	sleep 100
}
gdb_memory_map enable
sam7x.cpu configure -work-area-virt 0 -work-area-phys 0x00200000 -work-area-size 0x10000 -work-area-backup 0
flash bank sam7x.flash.0 at91sam7 0 0 0 0 sam7x.cpu 0 0 0 0 0 0 0 18432
flash bank sam7x.flash.1 at91sam7 0 0 0 0 sam7x.cpu 1 0 0 0 0 0 0 18432

Launching OpenOCD:

$ openocd -f at91sam7s512-jlink.cfg
Open On-Chip Debugger 0.9.0 (2017-03-07-13:28)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
adapter speed: 1000 kHz
srst_only srst_pulls_trst srst_gates_jtag srst_open_drain connect_deassert_srst
Info : J-Link ARM V8 compiled Dec  1 2009 11:42:48
Info : J-Link caps 0xb9ff7bbf
Info : J-Link hw version 80000
Info : J-Link hw type J-Link
Info : J-Link max mem block 9576
Info : J-Link configuration
Info : USB-Address: 0x0
Info : Kickstart power on JTAG-pin 19: 0xffffffff
Info : Vref = 3.332 TCK = 1 TDI = 0 TDO = 0 TMS = 0 SRST = 1 TRST = 1
Info : J-Link JTAG Interface ready
Info : clock speed 1000 kHz
Info : JTAG tap: sam7x.cpu tap/device found: 0x3f0f0f0f (mfg: 0x787, part: 0xf0f0, ver: 0x3)
Info : Embedded ICE version 1
Info : sam7x.cpu: hardware has 2 breakpoint/watchpoint units

Launching a telnet:

 telnet localhost 4444
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
> halt
target state: halted
target halted in ARM state due to debug-request, current mode: Supervisor
cpsr: 0xf00000d3 pc: 0x001c9c60
> flash erase_sector 0 0 15
erased sectors 0 through 15 on flash bank 0 in 0.033260s
> flash write_image /tmp/bootrom.s19 0x100000  
wrote 3624 bytes from file /tmp/bootrom.s19 in 0.392169s (9.024 KiB/s)

The chip was new but in case you need to backup the chip content first, this should be possible with sth like "dump_image original.bin 0x100000 0x80000"

Flashing full image

I also tried to flash the fullimage via JTAG but it failed working afterwards, so once the bootloader is installed, I used the usual recovery procedure:

• Press button and keep it pressed during the whole procedure
• Plug PM3 to USB
• ./flasher /dev/ttyACM0 fullimage.elf
• Release button and re-plug the PM3

Done

$ ./proxmark3 /dev/ttyACM0
Proxmark3 RFID instrument
bootrom: iceman/iceman/v2.1.0-1547-gb0df293d 2017-05-03 20:44:34
os: iceman/iceman/v2.1.0-1547-gb0df293d 2017-05-03 20:44:39
LF FPGA image built for 2s30vq100 on 2015/03/06 at 07:38:04
HF FPGA image built for 2s30vq100 on 2015/11/ 2 at  9: 8: 8

uC: AT91SAM7S512 Rev B
Embedded Processor: ARM7TDMI
Nonvolatile Program Memory Size: 512K bytes. Used: 217204 bytes (41%).
Free: 307084 bytes (59%).
Second Nonvolatile Program Memory Size: None
Internal SRAM Size: 64K bytes
Architecture Identifier: AT91SAM7Sxx Series
Nonvolatile Program Memory Type: Embedded Flash Memory