AM437X - LED toggle

Yuvaraj Ragupathi

HI,

I am trying to do LED toggle using PRU. My assembly code is

.origin 0
.entrypoint START

// GPIO3
#define GPIO3 0x481AE000
// GPIO5
#define GPIO5 0x48322000
#define GPIO_CLEARDATAOUT 0x190
#define GPIO_SETDATAOUT 0x194
#define GPIO_OE 0x134

START:
//set ARM such that PRU can write to GPIO
LBCO r0, C4, 4, 4
CLR r0, r0, 4
SBCO r0, C4, 4, 4

//base magic number for PWM
MOV r5, 250

//r6 is period (250 << 20)
LSL r6, r5, 20
//r5 is on_period (250 << 19) for 50% duty
LSL r5, r5, 19

// Configure as GPIO OUT 

MOV r3, GPIO3 | GPIO_OE
LBBO r2, r3, 0, 4
CLR r2, 2
SBBO r2, r3, 0, 4


//writes 7 to 8 user LEDs to turn on (no external hardware necessary)
PWM_ON:
    MOV r2, 3<< 6
    MOV r3, GPIO3 | GPIO_SETDATAOUT

    SBBO r2, r3, 0, 4

    MOV r4, 0

//wait until on_period is reached before turning off
//or wait until period to turn back on again
DELAY:
    ADD r4, r4, 1
    QBEQ PWM_ON, r4, r6
    QBNE DELAY, r4, r5

//writes 7 to 8 user LEDs to turn off
PWM_OFF:
    MOV r2, 3 << 6
    MOV r3, GPIO3 | GPIO_CLEARDATAOUT
    SBBO r2, r3, 0, 4
    QBA DELAY

Could you please correct me, if anything wrong in above code.

GPIO LED PINS are

GPIO3_18

GPIO3_7

GPIO3_8

GPIO5_10

GPIO5_11

GPIO5_12

GPIO5_13

GPIO5_14

On Host(ARM) Side Linux is running.

Regards,

Yuvaraj

over 11 years ago

0 Biser Gatchev-XID over 11 years ago

TI__Guru**** 393215 points

Hi Yuvaraj,

This forum only supports Linux. There are resources on the wiki for PRU that you can use:

http://processors.wiki.ti.com/index.php/AM18x_To_AM335x_Hardware_Migration_Guide#Programmable_Real-Time_Unit_SubSystem_.28PRUSS.29

http://processors.wiki.ti.com/index.php/Category:PRU

http://processors.wiki.ti.com/index.php/Programmable_Realtime_Unit

0 melissaw over 11 years ago in reply to Biser Gatchev-XID

TI__Genius 15990 points

Hi Yuvaraj,

What issue are you seeing?

A few basic things you might check:

- Are the pinmux setting correctly configured in the Control Module?

- Have you enabled the PRU to access memories external to the PRU-ICSS? (See this FAQ.)

Also, there is now a C-compiler for the PRU available through CCSv6. Details about the compiler and examples for using the C-compiler are available here: http://processors.wiki.ti.com/index.php/PRU-ICSS

Regards,

Melissa

0 Yuvaraj Ragupathi over 11 years ago in reply to melissaw

Prodigy 210 points

Hi Melissa,

Sorry for late reply.

PRU SYS CONFIG(0x26004)configured and value is

ICSS_PRU_SYS_CONFIG: 0x0000002a

GPIO Pin is having default setting and configured as GPIO out.

Note: When i power on the board 4 greeen LEDs are keep on blinking.

Regards,

Yuvaraj

0 vefone over 10 years ago in reply to Yuvaraj Ragupathi

Expert 2440 points

Hi,Yuvaraj

I think I faced the same problem like you.I configure the led pins in am437x-gp-evm.dts file like that:

leds {
pinctrl-names = "default", "sleep";
pinctrl-0 = <&user_leds_default>;
pinctrl-1 = <&user_leds_sleep>;

compatible = "gpio-leds";

led@0 {
label = "tl437x:green:heartbeat";
gpios = <&gpio5 9 GPIO_ACTIVE_HIGH>;
linux,default-trigger = "heartbeat";
default-state = "off";
};

led@1 {
label = "tl437x:green:mmc0";
gpios = <&gpio5 8 GPIO_ACTIVE_HIGH>;
linux,default-trigger = "mmc0";
default-state = "off";
};

led@2 {
label = "user-led0";
gpios = <&gpio5 10 GPIO_ACTIVE_HIGH>;
default-state = "on";
};

led@3 {
label = "user-led1";
gpios = <&gpio5 11 GPIO_ACTIVE_HIGH>;
default-state = "on";
};

led@4 {
label = "user-led2";
gpios = <&gpio5 12 GPIO_ACTIVE_HIGH>;
default-state = "on";
};

led@5 {
label = "user-led3";
gpios = <&gpio5 13 GPIO_ACTIVE_HIGH>;
default-state = "on";
};

};

and the pinmux are that:

user_leds_default: user_leds_default {
pinctrl-single,pins = <
0x238 (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_8.gpio5_8 */
0x23c (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_9.gpio5_9 */
0x240 (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_10.gpio5_10 */
0x244 (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_11.gpio5_11 */
0x248 (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_12.gpio5_12 */
0x24c (PIN_OUTPUT_PULLUP | MUX_MODE7) /* gpio5_13.gpio5_13 */
>;
};

user_leds_sleep: user_leds_sleep {
pinctrl-single,pins = <
0x238 (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_8.gpio5_8 */
0x23c (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_9.gpio5_9 */
0x240 (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_10.gpio5_10 */
0x244 (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_11.gpio5_11 */
0x248 (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_12.gpio5_12 */
0x24c (PIN_INPUT_PULLDOWN | MUX_MODE7) /* gpio5_13.gpio5_13 */
>;
};

but when I try to blink the led,it don't work.And I found that when I blink the led that not configure in am437x-gp-evm.dts like below,it really can work.

led@2 {
label = "user-led0";
gpios = <&gpio5 10 GPIO_ACTIVE_HIGH>;
default-state = "on";
};

now I don't know why .It seems that the pru cann't control the pins that we have configure in am437x-gp-evm.dts.Do you have some suggestion about that?

Here are my pru code.

/*
* main.c
*/
#include <stdint.h>
#include <pru_cfg.h>
#include "resource_table_empty.h"

/* LED port address */
#define GPIO5_BASE_ADDR 0x48322000
#define GPIO_OE_OFFSET 0x134
#define GPIO_CLRDATAOUT_OFFSET 0x190
#define GPIO_SETDATAOUT_OFFSET 0x194

volatile register uint32_t __R30;

volatile pruCfg CT_CFG __attribute__((cregister("PRU_CFG", near), peripheral));

int main(void) {

volatile uint32_t i;

/* GPI Mode 0, GPO Mode 0 */
CT_CFG.GPCFG0 = 0;
CT_CFG.SYSCFG_bit.STANDBY_INIT = 0;

volatile unsigned int led_set_addr;
volatile unsigned int led_modeset_addr;
volatile unsigned int led_clr_addr;

led_set_addr = GPIO5_BASE_ADDR + GPIO_SETDATAOUT_OFFSET;
led_clr_addr = GPIO5_BASE_ADDR + GPIO_CLRDATAOUT_OFFSET;

/* set led port as output IO */
led_modeset_addr = GPIO5_BASE_ADDR + GPIO_OE_OFFSET;
*(volatile unsigned int*)led_modeset_addr ^= 0xff00;

while(1) {

for (i = 0; i < 4; i++) {
__R30 = 1<<(i + 10);
*(volatile unsigned int*)led_set_addr |= __R30;
__delay_cycles(100000000); // half-second delay
*(volatile unsigned int*)led_clr_addr |= __R30;
__delay_cycles(100000000); // half-second delay
}
}
/* Halt the PRU core - shouldn't get here */
__halt();
}

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AM437X - LED toggle