1. Announcements

New AMA-2 page to collect another round of colleting information across dayNN pages and common issues and questions.

1.1. Homework comments

Use your list of terms and phrases from the Amp Hour podcast episode as your notice to figure out what they mean!

2. MCU to board communication links

Consider the hardware included in the SMART Response XE.

https://github.com/fdufnews/SMART-Response-XE-schematics and the PDF of the traced-out schematic.

  • Where is the Power button? How does it work?


Click for more information

The button is attached to a MCU pin and has an external pull-up resistor. So, when not pressed, the input value is high, and goes low when the button is pressed.

The pin is Port D, bit 2, which apparently is also connected to RXD1 and INT2 signals for some internal peripherals.

The INT2 is the key. When configured, a transition on this pin triggers an interrupt, which then starts the process of waking up the processor from sleep mode.

Find the SCK, MOSI, and MISO nodes, as labeled near the MCU, an ATmega128RFA1. These pins are 3 of the 4 pins of an SPI (Serial Peripheral Interface) link, the final pin is CS (chip-select) for each of the connected devices.

  • List out all of the things connected to this SPI bus from the MCU. Easy way is to look for CS_…​ node names.


Notes

3. Tasks vs SuperLoop

The TinyBASIC code that you get running on your unit is a hot mess. You may perhaps re-use some of the code, but certainly not in its current form.

What needs to happen in this device, in general?

  • LCD dot matrix screen

  • Keyboard

  • Packet radio (on the same die as the AVR MCU)