topic imx6q: Debugging LED in i.MX Processors

imx6q: Debugging LED

kimsuhak — Mon, 14 Jul 2014 02:38:12 GMT

Hello

Im using IMX6QAI board.

I want to turn on the debugging LED (D9).

The register is DISP0_DAT21. and use this as GPIO5_IO15 (ALT5)

Not, C code.

I want to use it in lowlevel_init.S in u-boot as an assembly code.

Do u have any idea for that ?

please help me.

Re: imx6q: Debugging LED

igorpadykov — Mon, 14 Jul 2014 03:23:04 GMT

Hi kim

syntax for writing to register is given in lowlevel_init.S as:

ldr r0, =AIPS2_ON_BASE_ADDR

ldr r1, =0x77777777

str r1, [r0, #0x0]

Main points below, refer to i.MX6DQ Reference Manual (rev.1 4/2013):

DISP0_DAT21 is GPIO5 module IO15 (bit 15 in register GPIOx_DR).

sect.28.5.3 GPIO direction register (GPIOx_GDIR),

sect.28.5.2 GPIO data register (GPIOx_DR),

sect.36.4.109 Pad Mux Register (IOMUXC_SW_MUX_CTL_PAD_DISP0_DATA21)

GPIO5 module address is 0x020A_C000 from Table 2-2 "AIPS-1 memory map"

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

Best regards

chip

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Re: imx6q: Debugging LED

kimsuhak — Mon, 14 Jul 2014 04:45:27 GMT

I coded urs in lowlevel_init.S

that was my code. but D9 doesn't work

Something missed?

.globl lowlevel_init

lowlevel_init:

inv_dcache

init_l2cc

init_aips

init_clock

mov pc, lr

ldr r0, = 0x020AC000

ldr r1, =0x00008000

str r1, [r0, #0x0]

str r1, [r0, #0x4]

ldr r0, = 0x020E0000

ldr r1, =0x00000015

str r1, [r0, #0x1C4]

Re: imx6q: Debugging LED

igorpadykov — Mon, 14 Jul 2014 13:21:20 GMT

Hi kim

please comment what are you doing with these codes.

Best regards

chip

Re: imx6q: Debugging LED

kimsuhak — Tue, 15 Jul 2014 00:46:51 GMT

Im solved.

I moved this code to cpu/.../start,S from lowlevel_init.S

I think something reset resigters of GPIO after .lowlevel_init.

It worked at the end of _arm_boot_start in start.S.

thanks for ur comments.