STM32

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STM32 programming

Boot mode configuration

BOOT1 BOOT0 Boot mode                              Address
  x     0   Main Flash memory                      0x8000000
  0     1   System memory (built-in bootloader)    0x1FFFB000
  1     1   Embedded SRAM                          0x20000000

  in Main flash memory and System memory boot modes address is aliased to 0x0


STM32F103C86T dev board boot pins

Legend

 o o o BOOT0
 o o o BOOT1
 ---
 |R|   Reset button
 ---

Boot to bootloader (built-in bootloader)

  • Allows flashing over USART
 o [=]
 [=] o
 ---
 |R|
 ---

Boot to main flash (user code)

 [=] o
 o o o
 ---
 |R|
 ---

Flashing

  • Flashing is done via USART1 (A9 TX A10 RX)

Converting Elf to Bin

Required if you only have elf files produced by your toolchain - stm32flash accepts only *.bin files. 

arm-none-eabi-objcopy -O binary miniblink.elf miniblink.bin

Using stm32flash

Test connection with 

stm32flash /dev/ttyUSB0

Flash and run from 0x0 

stm32flash /dev/ttyUSB0 -w miniblink.bin -g 0x0

Pinout

Stm32f103c8cb-pinlayout-wp01.jpg

Libraries

libopencm3

Minimalistic firmware library/framework.

Bootstrapping on Fedora

Library
dnf install arm-none-eabi*
mkdir embedded
git clone https://github.com/libopencm3/libopencm3
cd libopencm3
# Edit TARGETS in Makefile and keep only targets that you need (or just stm32/f1 for example).
make -j8
cd ..
DFU bootloader

This is a bootloader for Device Firmware Update via USB (stm32/f1). 

git clone https://git.48.io/libopencm3_dfu
cd libopencm3_dfu
# connect JTAG
make flash
# or flash via USART & stm32flash, see flashing section above
make stm32flash
Sample application

For use with DFU bootloader (stm32/f1). 

git clone https://git.48.io/libopencm3_template
cd libopencm3_template
# flash via dfu
make dfu
# or with JTAG
make flash
Library examples
git clone https://github.com/libopencm3/libopencm3-examples
# Either fetch git submodule pointing to libopencm3 and repeat steps in Library section
# or symlink libopecm3 dir to previously built libopencm3
cd libopencm3-examples
rmdir libopencm3
ln -s <PATH_TO-->/libopencm3 .
# try building miniblink example
cd examples/stm32/f1/stm32-h103/miniblink
make

Troubleshooting

  • use make V=1 when make fails
  • make sure openocd is not running when doing 'make flash'
Locked device

If you can't flash and 'make V=1 flash' reports something similar 

Info : Device Security Bit Set
stm32x unlocked

You need to unlock your device first (with JTAG): 

openocd -f jlink_swd_f103.cfg
telnet 127.0.0.1 4444
# in telnet issue:
stm32f1x unlock 0

Debugging

Debugging hardware

ST-Link clones or Discovery boards are flashable with Black Magic Probe firmware.

JLink

# add to Makefile to generate debuginfo
CXXFLAGS = -g

# run openocd
openocd -f jlink_swd_f103.cfg

# connect to openocd via gdb
arm-none-eabi-gdb --ex 'target remote localhost:3333' <EXECUTABLE>.elf
# Use following commands when in gdb (more at http://www.yolinux.com/TUTORIALS/GDB-Commands.html)
# c (continue), stop execution with Ctrl-C
# bt (stacktrace)
# b (break), e.g. 'b main' or 'b template.c:360'

Black Magic probe

Running BMP on Discovery boards

F3 Discovery

Shorting solder bridges SB13 and SB15 connects UART1 port from STM32F303 to STM32F103 making it possible to use Black Magic Probe as UART bridge via /dev/ttyACM1

F4 Discovery

To enable UART bridge via BMP on older F4 discovery (STM32F407) you need to solder wires between UART2 (PA2/PA3) on STM32F407 to pins PA2/PA3 on STM32F103. These are located in the corners of the chips. Take care when soldering PA3 on F407 as it's positioned near VSS, if you manage to short these pins try lifting PA3 from the pad completely soldering wire directly to it.

Flashing

To see device states during the process it is useful to open a second terminal and run 

dmesg -Hw

Next build firmware for stlink target and upload it to target 

# make PROBE_HOST=stlink
# flashing blackmagic_dfu via black magic probe
git clone https://github.com/blacksphere/blackmagic/
cd blackmagic
make PROBE_HOST=stlink
arm-none-eabi-gdb --ex 'target extended-remote /dev/ttyACM0' src/blackmagic_dfu
monitor swdp_scan
attach 1
monitor option erase
# restart target so it unlocks, repeat up to 'monitor option erase' then issue
load
# restart target, it should boot to black magic dfu
# [  +0.000002] usb 1-1.2: Product: Black Magic (Upgrade) for STLink/Discovery, (Firmware v1.6-rc0-257-gd6e2977)
# upload black magic via dfu
#
# disconnect your programmer so only target board is connected
#
sudo dfu-util -s 0x08002000:leave -D src/blackmagic.bin
# if dfu-util can't find your device you can specify -S <serial> from dmesg output
sudo dfu-util -S 7EBA7BA4 -s 0x08002000:leave -D src/blackmagic.bin

Sample session: 

$ arm-none-eabi-gdb --ex 'target extended-remote /dev/ttyACM0' src/blackmagic_dfu
Reading symbols from src/blackmagic_dfu...done.
Remote debugging using /dev/ttyACM0
(gdb) monitor swdp_scan
Target voltage: unknown
Available Targets:
No. Att Driver
 1      STM32F1 medium density
(gdb) attach 1
Attaching to program: /home/rmarko/embedded/blackmagic/src/blackmagic_dfu, Remote target
0x08010064 in ?? ()
(gdb) monitor option erase
0x1FFFF800: 0x0000
0x1FFFF802: 0x0000
0x1FFFF804: 0x0000
0x1FFFF806: 0x0000
0x1FFFF808: 0x0000
0x1FFFF80A: 0x0000
0x1FFFF80C: 0x0000
0x1FFFF80E: 0x0000
(gdb) load
Error erasing flash with vFlashErase packet
# ^^ target needs rebooting to unlock flash
(gdb) quit

<TARGET REBOOTED>

$ arm-none-eabi-gdb --ex 'target extended-remote /dev/ttyACM0' src/blackmagic_dfu
Reading symbols from src/blackmagic_dfu...done.
Remote debugging using /dev/ttyACM0
(gdb) monitor swdp_scan
Target voltage: unknown
Available Targets:
No. Att Driver
 1      STM32F1 medium density
(gdb) attach 1
Attaching to program: /home/rmarko/embedded/blackmagic/src/blackmagic_dfu, Remote target
0xfffffffe in ?? ()
(gdb) load
Loading section .text, size 0x1c48 lma 0x8000000
Loading section .data, size 0x90 lma 0x8001c48
Start address 0x8001498, load size 7384
Transfer rate: 11 KB/sec, 820 bytes/write.
(gdb) quit

<TARGET REBOOTED>

$ dmesg
[691195.851258] usb 1-1.6: new full-speed USB device number 112 using ehci-pci
[691195.943994] usb 1-1.6: New USB device found, idVendor=1d50, idProduct=6017
[691195.943997] usb 1-1.6: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[691195.943999] usb 1-1.6: Product: Black Magic (Upgrade) for STLink/Discovery, (Firmware v1.6.1-98-g9a5b31c)
[691195.944001] usb 1-1.6: Manufacturer: Black Sphere Technologies
[691195.944002] usb 1-1.6: SerialNumber: 7EBA7BA4

$ sudo dfu-util -S 7EBA7BA4 -s 0x08002000:leave -D src/blackmagic.bin
dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2016 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

dfu-util: Invalid DFU suffix signature
dfu-util: A valid DFU suffix will be required in a future dfu-util release!!!
Opening DFU capable USB device...
ID 1d50:6017
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 1024
DfuSe interface name: "Internal Flash   "
Downloading to address = 0x08002000, size = 60660
Download	[=========================] 100%        60660 bytes
Download done.
File downloaded successfully
Transitioning to dfuMANIFEST state

<TARGET REBOOTED>

$ dmesg
[691227.339977] usb 1-1.6: new full-speed USB device number 113 using ehci-pci
[691227.432954] usb 1-1.6: New USB device found, idVendor=1d50, idProduct=6018
[691227.432956] usb 1-1.6: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[691227.432957] usb 1-1.6: Product: Black Magic Probe (STLINK), (Firmware v1.6.1-98-g9a5b31c)
[691227.432958] usb 1-1.6: Manufacturer: Black Sphere Technologies
[691227.432959] usb 1-1.6: SerialNumber: 7EBA7BA4
[691227.433654] cdc_acm 1-1.6:1.0: ttyACM0: USB ACM device
[691227.434290] cdc_acm 1-1.6:1.2: ttyACM1: USB ACM device
Usage
arm-none-eabi-gdb --ex 'target extended-remote /dev/ttyACM0'
# Use following commands when in gdb
monitor swdp_scan
attach 1

Sample session: 

(gdb) monitor swdp_scan
Target voltage: unknown
Available Targets:
No. Att Driver
1      STM32F4xx
(gdb) attach 1
Attaching to Remote target
Error while running hook_stop:
Invalid type combination in equality test.
0x080035c2 in ?? ()
(gdb) bt
#0  0x080035c2 in ?? ()
#1  0x08001032 in ?? ()
#2  0x08001032 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

To access serial bridge: 

screen /dev/ttyACM1 115200
Tested boards
  • STLink programmers
  • STM32 F4 Discovery
  • STM32 IoT node (STM32L475)

Links

DMA

DAC

Docs

Calculating Timer Frequency

MUCH WIP

period_target_ms = p1 period_hz = p2

1000ms / p1 = p2

E.g. for 20ms (servo) period

1000ms / 20 ms = 50 hz

cpu_freq = 72Mhz prescale = 72

72MHz / 72 = 1Mhz

This increases out count register CNT by 1 000 000 each second. To calculate what is the correct value for the ARR register (which defines the period), we divide the result of the prescaled frequency by the intended frequency for our period:

1 000 000 Hz / 50 Hz = 20 000

Now every time the CNT register is increased by one, this is the equivalent to 1us. The duty cycle now could by set easily. E.g. for a 1.5ms duty cycle we set the CCRx register to 1500.


Stepper

driver_max_duty = 250khz

From http://www.kaltpost.de/?page_id=412

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