# Wish and Mist C99 on ESP8266

## Quick Wish on esp8266 instructions

To upload a program to the ESP8266 you need to put it in bootloader mode. There is usually a button for doing this, you must press and hold it during a hard reset for the chip to enter the bootloader's flash upload mode.

Required the first time on completely blank esp8266, or after flash_erase:

	make flash_erase	#to blank the chip
	make flash_all	#to upload program, and to enter default values to different parameters.

To erase the flash chip and upload new program:

* make flash_erase
* make flash_all
* make flash  :    Just upload the program

## Toolchain

We currently use our custom toolchain, which built on top of ESP8266_NONOS_SDK_V2.0.0_16_08_10, and the xtensa GCC compiler using these instructions:
port/esp8266/doc/toolchain/Toolchain.md

## Information on the esp8266 port

This project is the Wish and Mist c99 port to the esp8266 platform. The port supports several hardware environments:

* Sonoff S20
* 


## Important technical things to remember

### We have a custom linker script

Funtions without any section attributes will be placed in the flash by
 default, which is different from the "normal" behaviour of esp8266 SDKs.
 
 
### Flash usage
 
* Everything is setup for hardware with 1Mbyte flash. Devices with larger flash chip should be OK. 
* We have the spiffs in use. This places restrictions on how the "rf cal" sector introduced in SDK 1.5.x will be placed.

#### Changing flash size

Configuration of flash chip must be reflected in at least the following
places:

The LD script, where the length of the irom0 segment must be correct
(however it should must be inside the first 1024 Kbytes)

-in Makefile, in the esptool.py elf2image step, you should provide
--flash_size and --flash_mode correctly
(See flash chip's datasheet for supportted SPI modes (dual, quad..)

-in Makefile, the esptool.py write_flash step MUST have the correct
flash_size and flash_mode defined.