Attiny1614 One-Wire Errata Datasheet Errors

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Per request of Jim, publishing this in it's own thread.

originally reported here... https://www.avrfreaks.net/comment/2769991#comment-2769991

 

ATTINY1614

 

Datasheet says on pg337; "When the USART is set in one-wire mode, the transmitter and the receiver share the same RxD I/O pin."; (that is wrong)

One-Wire pin is the TXD pin, NOT THE RXD PIN

Microchip has confirmed that TXD is the correct pin for One-Wire. I'm in the process of trying to get Microchip to update the datasheet.

 

Also not specified in the datasheet for One-Wire mode...

If TX pin is set as output, ODME "Open Drain Mode Enable" does not work.
so TX port must NOT be set as output when using ODME "Open Drain Mode Enable".
This is Not specified in the datasheet.

 

The following statement from pg340 about one wire setup is vague.
For setting the USART in One-Wire mode, the following initialization sequence is recommended:
1) Set the TxD/RxD pin value high, and optionally set the XCK pin low.
*Needs clarification, what does "Set the TxD pin value high" mean, pullup resistors? or set as output?
*testing shows that in open drain mode, pin should NOT be set as output
2) Optionally, write the ODME bit in the USARTn.CTRLB register to '1' for Wired-AND functionality.
3) Set the TxD/RxD and optionally the XCK pin as an output.
4) Select the baud rate and frame format.
5) Select the mode of operation (enables XCK pin output in Synchronous mode).
6) Enable the transmitter or the receiver, depending on the usage

 

Tested and working method for 1 wire.
1) Do NOT set TxD pin as output
2) Enable Pullup Resistor on TxD pin if NOT using external pullup.
3) set bit LBME "Loop-back Mode Enable"
4) set bit ODME "Open Drain Mode Enable"
5) Use TxD pin for Transmit and Receive operations.
6) Enable the transmitter or the receiver, depending on the usage