August 2022

-Martin showed a W5500 ethernet board he purchased in Indonesia. It can be interfaced to any

microcontroller with a SPI bus eg EPS32.

-Andrew spoke about his project to use a single pin to communicate with 3 microcontrollers which control an XYZ plotter.

Minimal hardware:

Most devices will be 8 pin PIC12Fxxx devices (plus at least one 14 pin device)

All have Timer0 ( 8 bit prescaler and 8 bit register with roll-over interrupt)

Most (5 in the case of a PIC12Fxxx) pins can programmed to be either high Z input or a regular output pin.

Pulse formation is pull-down so to avoid transient issues due to software timing also add a moderate value pull-up resistor to the 1 bit bus.

Software Concepts:

Self-clocking long and short pulses based on use of Timer0.

Use a software 'token' which is passed around.

The address node that has the token becomes master.

The token is passed using the 'fake' device address zero.

There is no zero device.

But a message to device zero is a 'broadcast message' to all devices.

At power-up the device with the address 1 will always be 'first master'.

-A new member(Mark) attended the meeting at Pitt St. He discussed the work of an American inventor Royal Raymond Rife

who researched the use of radio frequencies to destroy disease organisms.

-Alex presented an update to the battery-powered Raspberry Pi project. An HC-06 bluetooth module was used to

provide a wireless link to the serial console.