Implement a bootloader.

This bootloader is now the application at 0x08000000 (FLASH start),
which the STM32 will execute upon reset.

The other applications are now loaded at 0x08030000 (128 KB into the
flash) and will never get started unless the bootloader has been
programmed into flash too.

1 files changed, 43 insertions, 33 deletions

diff --git a/README.md b/README.md
index aa259c1..3784aad 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,12 @@
-STM32 software for dev-bridge board
-===================================
+STM32 software for dev-bridge/Alpha board
+=========================================
 
 The dev-bridge board is a daughterboard for the Novena, which talks to the
 Novena's FPGA through the high-speed expansion connector.
 
+The Alpha board is a stand-alone board with an Artix-7 FPGA, a STM32 Cortex-M4
+microcontroller, two USB interfaces etc.
+
 See user/ft/stm32-dev-bridge/hardware/rev01 for schematics of the bridge
 board. There will be more information on the wiki shortly.
 
@@ -50,33 +53,51 @@ Do "bin/flash-target" from the top level directory (where this file is)
 to flash a built image into the microcontroller. See the section ST-LINK
 below for information about the actual hardware programming device needed.
 
+Example loading the bootloader and the led-test firmware to get some LEDs
+flashing:
+
+  $ make bootloader board-test
+  $ ./bin/flash-target projects/board-test/led-test
+  $ ./bin/flash-target projects/bootloader/bootloader
+
+At this point, the STM32 will reset into the bootloader which flashes the
+blue LED five times in one second, and then execution of the LED test
+firmware will begin. The LED test firmware will flash the green, yellow,
+red and blue LEDs in order until the end of time.
+
 
 ST-LINK
 =======
 To program the MCU, an ST-LINK adapter is used. The cheapest way to get
 one is to buy an evaluation board with an ST-LINK integrated, and pinouts
 to program external chips. This should work with any evaluation board from
-STM; we have tested with STM32F4DISCOVERY (with ST-LINK v2.0) and 
+STM; we have tested with STM32F4DISCOVERY (with ST-LINK v2.0) and
 NUCLEO-F411RE (with ST-LINK v2.1).
 
-The ST-LINK programming pins are the 1+4 throughole pads above the ARM
-on the circuit board. See the schematics for details, but the pinout
-from left to right (1, space, 4) of rev01 is
+The ST-LINK programming pins is called J1 and is near the CrypTech logo
+printed on the circuit board. The pin-outs is shown on the circuit board
+(follow the thin white line from J1 to the white box with STM32_SWD
+written in it). From left to right, the pins are
+
+  3V3, CLK, GND, I/O, NRST and N/C
 
-  NRST, space, CLK, IO, GND, VCC
+This matches the pin-out on the DISCO and NUCLEO boards we have tried.
 
 First remove the pair of ST-LINK jumpers (CN4 on the DISCO, CN2 on the
 NUCLEO). Then find the 6-pin SWD header on the left of the STM board (CN2
-on the DISCO, CN4 on the NUCLEO), and connect them to the dev-bridge
-board:
+on the DISCO, CN4 on the NUCLEO), and connect them to the Alpha board:
 
-* 5 T_NRST <-> NRST
-* 2 T_JTCK <-> CLK
-* 4 T_JTMS <-> IO
-* 3 GND <-> GND
+    NUCLEO / DISCO        CRYPTECH ALPHA
+    --------------        --------------
+* 1 VDD_TARGET        <-> 3V3
+* 2 SWCLK / T_JTCK    <-> CLK
+* 3 GND               <-> GND
+* 4 SWDIO / T_JTMS    <-> IO
+* 5 T_NRST / NRST     <-> NRST
 
-The dev-bridge board should be connected to the Novena and powered on
-before attempting to flash it.
+N/C (pin 6) means Not Connected.
+
+The Alpha board should be powered on before attempting to flash it.
 
 
 Debugging the firmware
@@ -87,24 +108,13 @@ firmware in an STM32:
 
   http://fun-tech.se/stm32/OpenOCD/gdb.php
 
-I've only managed to get the most basic text line gdb to work,
-something along these lines:
-
-1) Start OpenOCD server (with a configuration file for your type of ST-LINK
-   adapter)
-
-   $ openocd -f /usr/share/openocd/scripts/board/stm32f4discovery.cfg
-
-2) Connect to the OpenOCD server and re-flash already compiled firmware:
-
-   $ telnet localhost 4444
-   reset halt
-   flash probe 0
-   stm32f2x mass_erase 0
-   flash write_bank 0 /path/to/main.bin 0
-   reset halt
+There is a shell script called 'bin/debug' that starts an OpenOCD server
+and GDB. Example:
 
-3) Start GDB and have it connect to the OpenOCD server:
+  $ ./bin/debug projects/board-test/led-test
 
-   $ arm-none-eabi-gdb --eval-command="target remote localhost:3333" main.elf
+Once in GDB, issue "monitor reset halt" to reset the STM32 before debugging.
 
+Remember that the first code to run will be the bootloader, but if you do
+e.g. "break main" and "continue" you will end up in led-test main() after
+the bootloader has jumped there.