esp32: Use esptool.py to flash with 'make flash'

This flashes Zephyr at 0x1000: that's where the first stage bootloader, part of the ESP32 ROM, expects to find an "image header". The second-stage bootloader, part of ESP-IDF, isn't used by the Zephyr port. However, the bootloader can be used if desired; please refer to the ESP-IDF documentation on how to set up partitions tables and use the bootloader. The following environment variables will affect the ESP32 flashing process: Variable Default value ESP_DEVICE /dev/ttyUSB0 ESP_BAUD_RATE 921600 ESP_FLASH_SIZE detect ESP_FLASH_FREQ 40m ESP_FLASH_MODE dio ESP_TOOL espidf It's impossible to determine which serial port the ESP32 board is connected to, as it uses a generic RS232-USB converter. The default of /dev/ttyUSB0 is provided as that's often the assigned name on a Linux machine without any other such converters. The baud rate of 921600bps is recommended. If experiencing issues when flashing, try halving the value a few times (460800, 230400, 115200, etc). It might be necessary to change the flash frequency or the flash mode; please refer to the esptool documentation for guidance on these settings. If ${ESP_TOOL} is set to "espidf", the esptool.py script found within ESP-IDF will be used. Otherwise, this variable is handled as a path to the tool. Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>

Author: lpereira

boards/xtensa/esp32/Makefile.board

@@ -1,2 +1,3 @@
 EMU_PLATFORM ?=
 DEBUG_SCRIPT :=
+FLASH_SCRIPT := esp32.sh

scripts/support/esp32.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+
+ESP_DEVICE=${ESP_DEVICE:-/dev/ttyUSB0}
+ESP_BAUD_RATE=${ESP_BAUD_RATE:-921600}
+ESP_FLASH_SIZE=${ESP_FLASH_SIZE:-detect}
+ESP_FLASH_FREQ=${ESP_FLASH_FREQ:-40m}
+ESP_FLASH_MODE=${ESP_FLASH_MODE:-dio}
+ESP_TOOL=${ESP_TOOL:-espidf}
+
+cmd_flash() {
+local esptool
+local elf_name=${O}/${KERNEL_ELF_NAME}
+
+if [ "x${ESP_TOOL}" = "xespidf" ]; then
+esptool=${ESP_IDF_PATH}/components/esptool_py/esptool/esptool.py
+else
+esptool=${ESP_TOOL}
+fi
+if [ ! -x ${esptool} ]; then
+echo "esptool could not be found at ${esptool}"
+exit 1
+fi
+
+echo "Converting ELF to BIN"
+${esptool} --chip esp32 elf2image ${elf_name}
+
+echo "Flashing ESP32 on ${ESP_DEVICE} (${ESP_BAUD_RATE}bps)"
+${esptool} --chip esp32 \
+--port ${ESP_DEVICE} \
+--baud ${ESP_BAUD_RATE} \
+--before default_reset \
+--after hard_reset \
+write_flash \
+-u \
+--flash_mode ${ESP_FLASH_MODE} \
+--flash_freq ${ESP_FLASH_FREQ} \
+--flash_size ${ESP_FLASH_SIZE} \
+0x1000 ${elf_name/.elf/.bin}
+}
+
+CMD="$1"; shift
+case "${CMD}" in
+ flash)
+	cmd_flash "$@"
+	;;
+ *)
+ echo "${CMD} not supported"
+ exit 1
+	;;
+esac