tinyriscv-openocd/tcl/interface/raspberrypi-native.cfg

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Add BCM2835 (as found in Raspberry Pi) interface driver This adds support for JTAG programming by bitbanging GPIOs exposed on the RaspberryPi's expansion header. Tested by connecting directly to an STM32VLDiscovery board, without any additional circuity. I observed maximum about 4MHz on the TCK pin with an old analogue 'scope and about 100kHz when setting the speed to 100kHz. Busyloop waiting is needed because even with a single 0ns nanosleep call (with FIFO priority) it lowers the TCK speed to ~30kHz which is way too low to be useful. The speed testing with adapter_khz 2000 gave the following results: sudo chrt -f 1 nice -n -19 ./src/openocd \ -f interface/raspberrypi-native.cfg \ -c "set WORKAREASIZE 0x2000" \ -f target/stm32f1x.cfg -c "adapter_khz 2000" wrote 131072 bytes from file random.bin in 3.973677s (32.212 KiB/s) dumped 131072 bytes in 1.445699s (88.538 KiB/s) This is 3.7 times faster for writing and 14.3 times faster for reading compared to the generic sysfsgpio driver; probably the writing speed is limited by the target itself here and reading speed might be considerably higher too with appropriate connection and a capable target. BCM2835 name is choosen over BCM2708 because the published peripherals datasheet uses the particular model name and not family name. Change-Id: Ib78168be27f53c2a3c88c3dd8154d1190c318c78 Signed-off-by: Paul Fertser <fercerpav@gmail.com> Reviewed-on: http://openocd.zylin.com/758 Tested-by: jenkins Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>
2012-07-22 13:28:02 +00:00
#
# Config for using Raspberry Pi's expansion header
#
# This is best used with a fast enough buffer but also
# is suitable for direct connection if the target voltage
# matches RPi's 3.3V and the cable is short enough.
#
# Do not forget the GND connection, pin 6 of the expansion header.
#
interface bcm2835gpio
# Transition delay calculation: SPEED_COEFF/khz - SPEED_OFFSET
# These depend on system clock, calibrated for stock 700MHz
# bcm2835gpio_speed SPEED_COEFF SPEED_OFFSET
bcm2835gpio_speed_coeffs 113714 28
# Each of the JTAG lines need a gpio number set: tck tms tdi tdo
# Header pin numbers: 23 22 19 21
bcm2835gpio_jtag_nums 11 25 10 9
# If you define trst or srst, use appropriate reset_config
# Header pin numbers: TRST - 26, SRST - 18
# bcm2835gpio_trst_num 7
# reset_config trst_only
# bcm2835gpio_srst_num 24
# reset_config srst_only srst_push_pull
# or if you have both connected,
# reset_config trst_and_srst srst_push_pull