#c2tool
c2tool is a linux userspace application meant to enable in-system programming on low pin-count Silicon Labs devices using the Silicon Labs 2-Wire Interface (C2).
There is a linux kernel driver (drivers/misc/c2port) for this, but
- hardware support is quite limited
- sysfs interface is not very intuitive
local_irq_disable()affects real time performance- GPIOs can be easily accessed from userspace
##Challenge
The C2 Clock signal is shared with an active-low reset signal on the
target device. Any clock pulse taking longer than 20us is interpreted as a reset
signal. The kernel driver is driving the clock line with local_irq_disable()
pulled to make sure the timing is valid. But this degrades system performance.
c2tool depends on hardware support for generating clock pulses that are in the range from 20ns to 5000ns. In our reference application there is an FPGA but a discrete monoflop should also do.
Dependencies:
- libbfd
- libiberty
A simple "make" should be sufficient. More Makefile magic is welcome :)
##Prerequisites
Three gpios exported in /sys/class/gpio have to be supplied to c2tool:
- c2d: Read/write access to the C2 Data pin
- c2ck: Write access to the C2 Clock pin
- c2stb: A falling edge triggers a defined pulse on C2 Clock pin
All gpios must be configured as outputs and set to value 1.
Usage: c2tool [options] <gpio c2d> <gpio c2ck> <gpio c2ckstb> command
--version show version (0.01)
Commands:
info
Show information about connected device.
dump [offset] [len]
Dump flash memory of connected device.
flash [target <bfdname>] [adjust-start <incr>] <file>
Write file to flash memory of connected device.
erase
Erase flash memory of connected device.
verify [target <bfdname>] [adjust-start <incr>] <file>
Verify file to flash memory of connected device.
reset
Reset connected device.
- C2 Interface Specification
- Silabs Application Note 127: Fash programming via the C2 interface
- AN127 software