Data Sheet

Table Of Contents
ESP8266 Datasheet
Espressif Systems
Espressif Systems
June1,2015
15
/
32
Therefore, please choose the correct SPI mode when you are downloading into the flash, otherwise
firmwares/programs that you downloaded may not work in the right way.
2.7.
AHB and AHBBlocks
The AHB blocks performs the function of an arbiter, controls the AHB interfaces from the MAC, SDIO
(host) and CPU. Depending on the address, the AHB data requests can go into one of the two slaves:
APB block, or
flash controller (usually for standalone applications).
Data requests to the memory controller are usually high speed requests, and requests to the APB
block are usually registeraccess.
The APB block acts as a decoder. It is meant only for access to programmable registers within
ESP8266’s main blocks. Depending on the address, the APB request can go to the radio, SI/SPI, SDIO
(host), GPIO, UART, real-time clock (RTC), MAC or digital baseband.