README for the Expressif ESP32 Core board (V2)
==============================================
The ESP32 is a dual-core system from Expressif with two Harvard
architecture Xtensa LX6 CPUs. All embedded memory, external memory and
peripherals are located on the data bus and/or the instruction bus of
these CPUs. With some minor exceptions, the address mapping of two CPUs
is symmetric, meaning they use the same addresses to access the same
memory. Multiple peripherals in the system can access embedded memory via
DMA.
The two CPUs are named "PRO_CPU" and "APP_CPU" (for "protocol" and
"application"), however for most purposes the two CPUs are
interchangeable.
ESP32 Features
==============
* Address Space
- Symmetric address mapping
- 4 GB (32-bit) address space for both data bus and instruction bus
- 1296 KB embedded memory address space
- 19704 KB external memory address space
- 512 KB peripheral address space
- Some embedded and external memory regions can be accessed by either
data bus or instruction bus
- 328 KB DMA address space
* Embedded Memory
- 448 KB Internal ROM
- 520 KB Internal SRAM
- 8 KB RTC FAST Memory
- 8 KB RTC SLOW Memory
* External Memory
Off-chip SPI memory can be mapped into the available address space as
external memory. Parts of the embedded memory can be used as transparent
cache for this external memory.
- Supports up to 16 MB off-Chip SPI Flash.
- Supports up to 8 MB off-Chip SPI SRAM.
* Peripherals
- 41 peripherals
* DMA
- 13 modules are capable of DMA operation
ESP32 Toolchain
===============
You must use the custom Xtensa toolchain in order to build the ESP32 Core
BSP. The steps to build toolchain with crosstool-NG on Linux are as
follows:
git clone -b xtensa-1.22.x https://github.com/espressif/crosstool-NG.git
cd crosstool-NG
./bootstrap && ./configure --prefix=$PWD && make install
./ct-ng xtensa-esp32-elf
./ct-ng build
chmod -R u+w builds/xtensa-esp32-elf
These steps are given in setup guide in ESP-IDF repository:
https://github.com/espressif/esp-idf/blob/master/docs/linux-setup.rst#alternative-step-1-compile-the-toolchain-from-source-using-crosstool-ng
NOTE: The xtensa-esp32-elf configuration is only available in the
xtensa-1.22.x branch.
