DBUS (TI-Link) Demo

Bean

DBUS (or TI-Link) is a communication protocol used by TI calculators.
It's a pretty simple protocol but has some advantages over other more popular protocols.

A) It uses 2 wires that are pulled-up (much like I2C)
It has no set timing. Communication speed depends on the speed of the sender and receiver.
C) Uses a double handshake so no bits are lost even if interrupts or other processing occurs.

This simple demo program demonstrates the DBUS protocol. For the SX using the internal oscillator, DBUS is a good option because it is not timing dependent. It is also good for programs that must use an interrupt for other processing.

In my tests I got a frequency from the toggle pin of about 3.3Hz so that means it was sending 256 bytes 6.6 times a second or about 1700 bytes per second using nothing more than the internal pull-up. For high speed I would use a 1K pullup.

Enjoy,

Bean.


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Max Wooden

Thanks a lot Bean! This is great. I've been wanting to mess around with sending data between a SX and my calculator.

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Max Wooden
Reedley, California

Bean

Max,
I don't know if the TI calculators use the exact same format.
I added the start bit requirement to keep things in sync.

Bean.

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Max Wooden

I seem to remember the start bit requirement from when I last read over the protocol. This will serve as a great starting point!

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Max Wooden
Reedley, California