Add doc : using OpenOCD and STLinkV2 to flash the firmware

README.md

@@ -52,6 +52,7 @@ As of now, here is the list of achievements of this project:
  - [Versioning](doc/versioning.md)
  - [Files included in the release notes](doc/filesInReleaseNotes.md)
  - [Build the project](doc/buildAndProgram.md)
+ - [Flash the firmware using OpenOCD and STLinkV2](doc/openOCD.md)
  - [Build the project with Docker](doc/buildWithDocker.md)
  - [Bootloader, OTA and DFU](./bootloader/README.md)
  - [Stub using NRF52-DK](./doc/PinetimeStubWithNrf52DK.md)

doc/openOCD.md

@@ -0,0 +1,105 @@
+# OpenOCD and STLink
+OpenOCD (**Open O**n **C**hip **D**ebugger) is an open source tool that interfaces with many SWD/JTAG debugger to provide debugging and *in-system* programming for embedded target devices.
+
+It supports the **NRF52** (the CPU of the PineTime) and the **STLinkV2**, a cheap SWD debugger.
+
+It works on X86 computers, as well as ARM/ARM64 computers and SBC (like the RaspberryPi and Pine64 Pinebook Pro) !
+
+## Installation
+We will build OpenOCD from sources, as packages from Linux distributions are most of the time outdated and do not support the NRF52 correctly. 
+
+ - Fetch the sources from GIT, and build and install it:
+
+```
+git clone https://^Ct.code.sf.net/p/openocd/code openocd-code
+
+cd openocd-code
+
+./bootstrap
+./configure --enable-stlink
+make -j 4
+sudo make install
+```
+
+ - Configure UDEV to allow OpenOCD to open the interface to your STLinkV2:
+```
+sudo cp contrib/60-openocd.rules /etc/udev/rules.d/
+sudo udevadm control --reload-rules
+```
+
+ - You can now plug your STLinkV2 in a USB port and run OpenOCD to see if it's working correctly:
+
+```
+$ openocd -f interface/stlink.cfg -f target/nrf52.cfg
+Open On-Chip Debugger 0.10.0+dev-01411-g051e80812-dirty (2020-09-28-20:16)
+Licensed under GNU GPL v2
+For bug reports, read
+        http://openocd.org/doc/doxygen/bugs.html
+Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.
+Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
+
+nRF52 device has a CTRL-AP dedicated to recover the device from AP lock.
+A high level adapter (like a ST-Link) you are currently using cannot access
+the CTRL-AP so 'nrf52_recover' command will not work.
+Do not enable UICR APPROTECT.
+
+Info : Listening on port 6666 for tcl connections
+Info : Listening on port 4444 for telnet connections
+Info : clock speed 1000 kHz
+Info : STLINK V2J34S7 (API v2) VID:PID 0483:3748
+Info : Target voltage: 3.294340
+Error: init mode failed (unable to connect to the target)
+```
+Ok, OpenOCD is running and it detects my STLinkV2. The last error shows that I've not connected the STLinkV2 to the PineTime.
+
+## Configuration files
+OpenOCD is configured using configuration files.
+First, we need a common configuration file for the project : **openocd-stlink.ocd**:
+```
+source [find interface/stlink.cfg]
+
+gdb_flash_program enable
+gdb_breakpoint_override hard
+
+source [find target/nrf52.cfg]
+```
+This file specifies to OpenOCD which debugger and target it will be connected to..
+
+Then, we use various *user files* to use OpenOCD to flash InfiniTime binary files.
+
+This files flashes the bootloader and the application firmware : **flash_bootloader_app.ocd**:
+```
+init
+
+program <build directory>/bootloader.bin verify 0x00000000
+program <build directory>/image-0.8.2.bin verify 0x00008000
+
+reset
+```
+
+And this one flashes the graphics flasher (it writes the bootloader graphics into the SPI NOR flash memory) : **flash_graphics.ocd**:
+```
+init
+
+program <build directory>/pinetime-graphics-0.8.2.bin verify 0x00000000
+
+reset
+```
+
+## Examples
+### Flash bootloader and application
+```
+openocd -f ./openocd-stlink.cfg -f ./flash_bootloader_app.ocd
+```
+
+### Flash graphics flasher
+```
+openocd -f ./openocd-stlink.cfg -f ./flash_graphics.ocd
+```
+
+## Connect the STLinkV2 to the PineTime
+Here is an example using the pogo pins:
+![SWD pinout](../images/swd_pinout.jpg)
+![Pogo pins](../images/pogopins.jpg)
+
+You can find more information about the SWD wiring [on the wiki](https://wiki.pine64.org/index.php?title=PineTime_devkit_wiring).