# Serial and GPIOs on A1300 Slate Plus

**URL:** <https://forum.gl-inet.com/t/serial-and-gpios-on-a1300-slate-plus/31150>\
**Category:** Router\
**Created:** [July 6, 2023, 3:46pm UTC](https://forum.gl-inet.com/t/serial-and-gpios-on-a1300-slate-plus/31150 "2023-07-06T15:46:46Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jolouis](https://forum-assets.gl-inet.com/letter_avatar_proxy/v4/letter/j/f19dbf/32.png) [@jolouis](https://forum.gl-inet.com/u/jolouis)\
**Post date:** [July 6, 2023, 3:46pm UTC](https://forum.gl-inet.com/t/serial-and-gpios-on-a1300-slate-plus/31150/1 "2023-07-06T15:46:46Z")

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We are using Slate Plus for an upcoming project and one of the requirements is to have GPIO available. The official GL documentation used to be very good and itemizing out GPIOs but these days it seems they gloss over things and you have to go digging through source code to see for real.

We have found through checking the DTS that the serial pins and “i2c” pins are both attached to GPIOs to operate:  
serial\_pins: serial\_pinmux {  
mux {  
pins = “gpio60”, “gpio61”;  
function = “blsp\_uart0”;  
bias-disable;  
};  
};

```
    i2c_0_pins: i2c_0_pinmux {
            pinmux {
                    pins = "gpio58", "gpio59";
                    function = "blsp_i2c0";
                    bias-disable;
            };
    };

```

I know serial pins are exposed on this board, and we might be able to use those if we sacrifice serial functions. Two questions:

1. is i2c exposed or used for anything on the a1300? I do not see headers or pins anywhere on the board, but maybe they just are not labelled/documented well? or are those pins not connected to anything?
2. Anyone ever tried to reduce the serial port to a single pin instead of both RX and TX? in our case having simply TX would be enough that if there is a crash we could see what was going on. Would prefer not to sacrifice the serial port completely but not sure if that is an option.

Any feedback welcome!

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**Author:** ![dxf](https://forum-assets.gl-inet.com/letter_avatar_proxy/v4/letter/d/41988e/32.png) [@dxf](https://forum.gl-inet.com/u/dxf)\
**Post date:** [July 7, 2023, 3:13am UTC](https://forum.gl-inet.com/t/serial-and-gpios-on-a1300-slate-plus/31150/2 "2023-07-07T03:13:13Z")

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For first question:  
The i2c is used to control the ET6326 to realize the breathing function of the led. which is implemented in /usr/bin/gl\_i2c\_led and you can refer to this link to learn about its implementation.

> [@GL-MT1300 LED control instructions](https://forum.gl-inet.com/t/gl-mt1300-led-control-instructions/13338):
>
> #stop glinet control /etc/init.d/led stop /etc/init.d/led disable #reset I2C IC echo 0 \> /sys/class/leds/gl-mt1300:blue/brightness echo 0 \> /sys/class/leds/gl-mt1300:white/brightness i2cset -f -y 0 0x30 0x00 0x1F i2cset -f -y 0 0x30 0x00 0x1A #adjust brightness i2cset -f -y 0 0x30 0x06 0x3f #blue 0x3f \* 0.125mA = 8mA i2cset -f -y 0 0x30 0x07 0x7f #white 0x7f \* 0.125mA = 16mA #light up LED i2cset -f -y 0 0x30 0x04 0x01 i2cset -f -y 0 0x30 0x04 0x04 #put out LED i2cset -f -…

For second question:  
I think you need to modify the driver to implement it, or you can refer to this patch? I think you should also encounter other difficulties, if you realize, I hope you can share with me.  
[https://github.com/gl-inet/gl-infra-builder/blob/main/patches-mt798x-7.6.6.1/3008-support-uart1-no-use-cts-and-rts.patch](https://github.com/gl-inet/gl-infra-builder/blob/main/patches-mt798x-7.6.6.1/3008-support-uart1-no-use-cts-and-rts.patch)

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**Author:** ![bruce](https://forum-assets.gl-inet.com/user_avatar/forum.gl-inet.com/bruce/32/35649_2.png) [@bruce](https://forum.gl-inet.com/u/bruce)\
**Post date:** [October 29, 2025, 4:22am UTC](https://forum.gl-inet.com/t/serial-and-gpios-on-a1300-slate-plus/31150/3 "2025-10-29T04:22:56Z")

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