<![CDATA[stampS3 capacitive touch detect : GPIO#3 NOT working??]]>Now making a tool with 12 capacitive touch sensors using stampS3 on Arduino.
I am confusing why touch detect does not work well when using GPIO#3pin.
I have confirmed that pin define WITHOUT GPIO#3pin , it works well.
I have confirmed that both of my two stampS3 show the same result with nothing connected to stampS3.

I may not understand well of official documents, can you tell me where to read?

quotation of my Arduino program
........
#define numSW 12 //define number of touch SWs
int TOUCH_PIN[numSW] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13 }; //define GPIO number for.each touchSW
.....
void serialPrintThresh() { //読み取り値と閾値を列記
for (int touchNum = 0; touchNum < numSW; touchNum++) {
USBSerial.print(touchNum + 1); //+1してピン番号に換算
USBSerial.print(": ");
USBSerial.print(touchRead(TOUCH_PIN[touchNum]));
USBSerial.print(" / ");
USBSerial.print(threshold[touchNum]);
USBSerial.println(" ");
}
}

......serial print result:
......many GPIO pins show big number, not only #3
......only #1 pin can detect touch well, BUT others can not !

1: 13859 / 2764
2: 13998 / 2799
3: 2443023 / 488604
4: 2783227 / 556645
5: 4178149 / 835629
6: 1179519 / 235903
7: 4060029 / 812005
8: 1920687 / 384137
9: 4003023 / 800604
10: 893757 / 178751
11: 3026140 / 605228
12: 3399653 / 679930

_____________modified program, exchange #3 to #12

int TOUCH_PIN[numSW] = { 1, 2, 12, 4, 5, 6, 7, 8, 9, 10, 11, 13 }; //define GPIO number for.each touchSW
..........all pins shows similar number
..........each pin detect touch well !

1: 13840 / 2758
2: 13982 / 2796
3: 13921 / 2770 // #12GPIO pin
4: 13443 / 2680
5: 12204 / 2434
6: 12192 / 2427
7: 12522 / 2495
8: 11920 / 2377
9: 12530 / 2501
10: 12662 / 2533
11: 20303 / 4060
12: 13899 / 2779

]]>https://community.m5stack.com/topic/5432/stamps3-capacitive-touch-detect-gpio-3-not-workingRSS for NodeSat, 09 May 2026 13:50:37 GMTWed, 28 Jun 2023 02:16:38 GMT60<![CDATA[Reply to stampS3 capacitive touch detect : GPIO#3 NOT working?? on Sat, 01 Jul 2023 23:58:28 GMT]]>@felmue
thanks!
I will change my PCB design not to use GPIO#3 for capacitive touch detect.

]]>https://community.m5stack.com/post/21428https://community.m5stack.com/post/21428Sat, 01 Jul 2023 23:58:28 GMT<![CDATA[Reply to stampS3 capacitive touch detect : GPIO#3 NOT working?? on Wed, 28 Jun 2023 21:50:09 GMT]]>Hello @sunshine

I don't know if G3 could be used a touch detect with the pull-up in place. Sorry.

Thanks
Felix

]]>https://community.m5stack.com/post/21370https://community.m5stack.com/post/21370Wed, 28 Jun 2023 21:50:09 GMT<![CDATA[Reply to stampS3 capacitive touch detect : GPIO#3 NOT working?? on Wed, 28 Jun 2023 09:02:05 GMT]]>@felmue
Thank you for your prompt reply.
On the same document showing pin assignment of stampS3, I thought that G3 can be used for TCH3 same as others.
But I understand that G3 can not be used for touch detect as others.
And, other touch pins do not work as touch pins affected by G3 pin assignment for touch, is more serious issue for me.
If you know, can I use with some special treatment for G3 ? eg. it can be used as touch detect after certain time passed after boot time?

]]>https://community.m5stack.com/post/21360https://community.m5stack.com/post/21360Wed, 28 Jun 2023 09:02:05 GMT<![CDATA[Reply to stampS3 capacitive touch detect : GPIO#3 NOT working?? on Wed, 28 Jun 2023 05:06:01 GMT]]>Hello @sunshine

GPIO0, GPIO3, GPIO45 and GPIO46 are so called strapping pins which are used to setup various things at boot time.

In the M5StampS3 schematic you'll see that an external 10 k pull-up resistor has been connected to GPIO3. I guess that's the reason for the values you are getting.

Thanks
Felix

]]>https://community.m5stack.com/post/21358https://community.m5stack.com/post/21358Wed, 28 Jun 2023 05:06:01 GMT