Hi, newbie here. I'm trying to use Teensy 4.1 to perform some UART serial communication task.
The schematic is shown as below
To verify my design, I wrote a simple code to transmit data via Teensy and measure the voltage at the other end.
Source Code
void setup() {
pinMode(1, OUTPUT);
pinMode(8, OUTPUT);
pinMode(35, OUTPUT);
pinMode(29, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH);
digitalWrite(8, HIGH);
digitalWrite(35, HIGH);
digitalWrite(29, HIGH);
delay(1000);
digitalWrite(1, LOW);
digitalWrite(8, LOW);
digitalWrite(35, LOW);
digitalWrite(29, LOW);
delay(1000);
}
But only Serial 1 and 2 are working as expected. 7 and 8 is not working as the voltage measured is about 2.1V instead of toggling between 3.3 and 0V.
I have no idea why the identical design could provide different behaviors from the other end.
Without the digital isolator, all the serial are working as expected.
I was wondering is it because of the strong pullup(s) being used (100ohm) causing the issue, but why is it happened on both serial 7 and 8 only? I couldn't find any specific reason to this and thats why I'm here to seek help from experts
: )
Remarks:
RxTx are connected to Teensy
Tx out are used to measured the voltage
3v3 is connect below pin12 of teensy
The schematic is shown as below
To verify my design, I wrote a simple code to transmit data via Teensy and measure the voltage at the other end.
Source Code
void setup() {
pinMode(1, OUTPUT);
pinMode(8, OUTPUT);
pinMode(35, OUTPUT);
pinMode(29, OUTPUT);
}
void loop() {
digitalWrite(1, HIGH);
digitalWrite(8, HIGH);
digitalWrite(35, HIGH);
digitalWrite(29, HIGH);
delay(1000);
digitalWrite(1, LOW);
digitalWrite(8, LOW);
digitalWrite(35, LOW);
digitalWrite(29, LOW);
delay(1000);
}
But only Serial 1 and 2 are working as expected. 7 and 8 is not working as the voltage measured is about 2.1V instead of toggling between 3.3 and 0V.
I have no idea why the identical design could provide different behaviors from the other end.
Without the digital isolator, all the serial are working as expected.
I was wondering is it because of the strong pullup(s) being used (100ohm) causing the issue, but why is it happened on both serial 7 and 8 only? I couldn't find any specific reason to this and thats why I'm here to seek help from experts
: )
Remarks:
RxTx are connected to Teensy
Tx out are used to measured the voltage
3v3 is connect below pin12 of teensy