rBoot and OTA updating

Introduction

rBoot is an open source bootloader for the ESP8266, which is now fully integrated with Sming. rBoot is a more flexible alternative to the closed source bootloader supplied by Espressif with the SDK. A bootloader allows you to have more than one application on the esp8266, either completely different apps, or different version of the same app, which can be updated over the air.

The example Basic_rBoot demonstrates the use of rBoot, but if you want to add it to an existing project this little tutorial will guide you.

Need to know

• The esp8266 can only memory map 1mb of flash at a time, your rom must fit within the a single 1mb block of flash.
• Different 1mb blocks can be mapped at different times, so your rom does not have to be within the first 1mb block. The support for this in rBoot is called big flash mode. A single compiled and linked rom image can be placed at the same relative position in any 1mb block of flash.
• If you have two smaller roms in a single 1mb of flash (your only option if you flash is 1mb or smaller) this is referred to as two rom mode in rBoot. Each rom needs to be separately linked to have the correct memory mapped flash offset. Examples are given below for common scenarios.

Setting up build environment

• Make sure your Makefile has the following code at the bottom, if you have copied a sample since Sming v1.3.0 this will already be there:

# Include main Sming Makefile
ifeq ($(RBOOT_ENABLED), 1)
include $(SMING_HOME)/Makefile-rboot.mk
else
include $(SMING_HOME)/Makefile-project.mk
endif

• Add the following variables to Makefile-user.mk:

#### overridable rBoot options ####
## use rboot build mode
RBOOT_ENABLED ?= 1
## enable big flash support (for multiple roms, each in separate 1mb block of flash)
RBOOT_BIG_FLASH ?= 1
## two rom mode (where two roms sit in the same 1mb block of flash)
RBOOT_TWO_ROMS  ?= 0
## size of the flash chip
SPI_SIZE        ?= 4M
## output file for first rom (.bin will be appended)
#RBOOT_ROM_0     ?= rom0
## input linker file for first rom
#RBOOT_LD_0      ?= rom0.ld
## these next options only needed when using two rom mode
#RBOOT_ROM_1     ?= rom1
#RBOOT_LD_1      ?= rom1.ld
## size of the spiffs to create
#SPIFF_SIZE      ?= 65536
## option to completely disable spiffs
DISABLE_SPIFFS  = 1
## flash offsets for spiffs, set if using two rom mode or not on a 4mb flash
## (spiffs location defaults to the mb after the rom slot on 4mb flash)
#RBOOT_SPIFFS_0  ?= 0x100000
#RBOOT_SPIFFS_1  ?= 0x300000
## esptool2 path
#ESPTOOL2        ?= esptool2

• Copy rom0.ld from the Basic_rBoot sample to your project.

Building

• The options above are perfect for a 4mb flash, if this is what you have (e.g. an esp-12) you don't need to do anything else. Otherwise see information below about configuration.
• Run make as normal, rBoot and your app rom will both be built for you.
• Running make flash will flash rBoot and the first rom slot.

Configuring for two rom mode

If you have a 1mb flash, you will need to have two 512kb rom slots, both in the same 1mb block of flash. Set the following options in Makefile-user.mk

RBOOT_ENABLED   ?= 1
RBOOT_BIG_FLASH ?= 0
RBOOT_TWO_ROMS  ?= 1
SPI_SIZE        ?= 1M

Spiffs

To use spiffs think about where you want your spiffs to sit on the flash. If you have a 4mb flash the default position is for the first rom to be placed in the first 1mb block and the second rom to be placed in the third 1mb block of flash. This leaves a whole 1mb spare after each rom in which you can put your spiffs. If you have to a smaller flash the spiffs will have to share the 1mb block with the rom e.g. first part of each 1mb block contains the rom and the second part contains the spiffs (does not have to be split equally in half). So for the 4mb example you could put the spiffs for your first rom at flash address at 0x100000 and the spiffs for your second rom at 0x300000 (in each case that is the 1mb block after the rom).

To mount your spiffs at boot time add the following code to init:

int slot = rboot_get_current_rom();
if (slot == 0) {
	//debugf("trying to mount spiffs at %x, length %d", RBOOT_SPIFFS_0 + 0x40200000, SPIFF_SIZE);
	spiffs_mount_manual(RBOOT_SPIFFS_0 + 0x40200000, SPIFF_SIZE);
} else {
	//debugf("trying to mount spiffs at %x, length %d", RBOOT_SPIFFS_1 + 0x40200000, SPIFF_SIZE);
	spiffs_mount_manual(RBOOT_SPIFFS_1 + 0x40200000, SPIFF_SIZE);
}

The addition of 0x40200000 is due to a Sming quirk, just ignore it.

Over-the-air (OTA) updates Add the following code:

rBootHttpUpdate* otaUpdater = 0;

void OtaUpdate_CallBack(bool result) {
	if (result == true) {
		// success
		uint8 slot;
		slot = rboot_get_current_rom();
		if (slot == 0) slot = 1; else slot = 0;
		// set to boot new rom and then reboot
		Serial.printf("Firmware updated, rebooting to rom %d...\r\n", slot);
		rboot_set_current_rom(slot);
		System.restart();
	} else {
		// fail
		Serial.println("Firmware update failed!");
	}
}

void OtaUpdate() {

	uint8 slot;
	rboot_config bootconf;

	// need a clean object, otherwise if run before and failed will not run again
	if (otaUpdater) delete otaUpdater;
	otaUpdater = new rBootHttpUpdate();
	
	// select rom slot to flash
	bootconf = rboot_get_config();
	slot = bootconf.current_rom;
	if (slot == 0) slot = 1; else slot = 0;

#ifndef RBOOT_TWO_ROMS
	// flash rom to position indicated in the rBoot config rom table
	otaUpdater->addItem(bootconf.roms[slot], ROM_0_URL);
#else
	// flash appropriate rom
	if (slot == 0) {
		otaUpdater->addItem(bootconf.roms[slot], ROM_0_URL);
	} else {
		otaUpdater->addItem(bootconf.roms[slot], ROM_1_URL);
	}
#endif

	// use user supplied values (defaults for 4mb flash in makefile)
	if (slot == 0) {
		otaUpdater->addItem(RBOOT_SPIFFS_0, SPIFFS_URL);
	} else {
		otaUpdater->addItem(RBOOT_SPIFFS_1, SPIFFS_URL);
	}

	// set a callback
	otaUpdater->setCallback(OtaUpdate_CallBack);

	// start update
	otaUpdater->start();
}

You will need to define ROM_0_URL, ROM_0_URL and SPIFFS_URL with http urls for the files to download.