Shulou(Shulou.com)06/03 Report--

First briefly analyze the uboot startup process

Make am335x_evm, corresponding to boards.cfg:

Am335x_evm arm armv7 am335x ti am33xx am335x_evm:SERIAL1,CONS_INDEX=1

So the corresponding starting address is in the / arch/arm/cpu/armv7/start.S file.

Board level initialization initializes the peripheral pin setting in the s_init function.

A8_LED is connected to R6 of am335x, corresponding to the

MODE:7,GPIO2_25.

Define the module_pin_mux structure GPIO2_25

Static struct module_pin_mux GPIO2_25 [] = {{OFFSET (lcd_ac_bias_en), (MODE (7))}, / * LED * / {- 1},}

GPIO2_25 corresponds to serial number 32 "2" 25 = 89 to apply for access to GPIO2_25

Gpio_request (89, "led")

Set IO to output mode

Gpio_direction_output (89d0)

Set IO to low level and LED light on

Gpio_set_value (89d0)

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.