How to master/slave Arduino UNO->Teensy 3.6
- Thread starter dark4eg
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PaulStoffregen
Well-known member
Teensy 3.6 is not 5V tolerant. You will need to use resistors or level translators to reduce its 5V signals to the 3.3V levels.
Uno can read the 3.3V signals, so there's usually no need to increase them to 5V.
Uno can read the 3.3V signals, so there's usually no need to increase them to 5V.
PaulStoffregen
Well-known member
SoftwareSerial on Uno to Serial1 on Teensy is probably the simplest. You will need a pair of resistors to decrease Uno's output to 3.3V. Best to test with a voltmeter before you connect it to Teensy 3.6.
The other viable option would be Wire, where one side runs master mode and the other side slave mode. The Wire lib comes with examples. Uno has very weak pullups to 5V. If you connect 2.2k resistor pullups to 3.3V, the SDA and SCL signals will be very close to 3.3V when high. That should also work. The Wire lib is nice for passing messages. It's more complicated than if you only send single bytes with serial, but if you send lots of complex messages it can be simpler than having to parse where each message begins as serial receives the bytes.
The other viable option would be Wire, where one side runs master mode and the other side slave mode. The Wire lib comes with examples. Uno has very weak pullups to 5V. If you connect 2.2k resistor pullups to 3.3V, the SDA and SCL signals will be very close to 3.3V when high. That should also work. The Wire lib is nice for passing messages. It's more complicated than if you only send single bytes with serial, but if you send lots of complex messages it can be simpler than having to parse where each message begins as serial receives the bytes.
Oh.
https://www.arduino.cc/en/Tutorial/MasterWriter this example does not work.
In my case, you will need to connect UNO-> GND <-Teensy?
https://www.arduino.cc/en/Tutorial/MasterWriter this example does not work.
In my case, you will need to connect UNO-> GND <-Teensy?
PaulStoffregen
Well-known member
Yes, same as when connecting 2 regular Arduino boards, you need 3 wires: GND, SDA (A4 pin), SCL (A5 pin).
Unlike regular Arduino, you must also connect a 2.2K resistor from SDA to 3.3V, and another 2.2K resistor from SCL to 3.3V.
Run master_writer on one side and slave_receiver on the other side. Also, when you program each board, pay attention to the address numbers. They need to match. Look for these:
You can use any number from 1 to 127, though there's a convention that 1 to 7 are best to save for special uses. Just make sure it's the same on both sides.
Unlike regular Arduino, you must also connect a 2.2K resistor from SDA to 3.3V, and another 2.2K resistor from SCL to 3.3V.
Run master_writer on one side and slave_receiver on the other side. Also, when you program each board, pay attention to the address numbers. They need to match. Look for these:
Code:
Wire.beginTransmission(9); // transmit to device #9
Code:
Wire.begin(9); // join i2c bus with address #9You can use any number from 1 to 127, though there's a convention that 1 to 7 are best to save for special uses. Just make sure it's the same on both sides.
PaulStoffregen
Well-known member
If that doesn't solve the problem, please post a photo of how you're actually connecting everything.
Sometimes the problem can be as simple as a misunderstanding about how to connect the wires. Also, check out this quick video about how to solder Teensy. It has been a misunderstanding in some cases....
Sometimes the problem can be as simple as a misunderstanding about how to connect the wires. Also, check out this quick video about how to solder Teensy. It has been a misunderstanding in some cases....
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