8-bit - STM8 Breakout board

 Projects / Misc 8-bit uC projects  Original post date:11/25/2016

While I am waiting for the STLink to show up in my mail box, I might as well write down the check list.

Design

I am just going to throw in a 0.1uF cap for high frequency decoupling as the part is relatively low power. The regulator design would look after the bulk decoupling requirement. This cap should be on the breakout.

Reset

Vcap requirement

Vcap is the external decoupling for the core voltage (1.8V for STM8S003) generated by an on-chip regulator.

The ESR value pretty much means it has to be a ceramic capacitor. I am going to pick a 1uF X7R ceramic SMT 0603. Allowing for 2nH in a ceramic cap which leaves about 13nH for traces/wires.
Since the breakout PCB doesn't have a proper ground plane, I use the following for approximation. This cap should be on the breakout. 2 cm is going to be an issue for an external through hole part on a breadboard.

http://chemandy.com/calculators/flat-wire-inductor-calculator.htm

This is the minimal circuit.

Programming/debugging is via SWIM. ST has defined the following pinout.

After 8+ weeks of wait, my ST-Link clone finally arrived today. They must have something like the Indiania Jones warehouse (Hanger 51) at Canada Custom for storing 7+ weeks worth of packages waiting to be inspected.

I have soldered the STM8S003F3 onto a breakout board from here. I drilled a couple of 0.8mm (0.031") dia. holes and connected the optional crystal (blue wires) to pin 5 & 6 and the 22pF load capacitors (in white) to ground.  It is optional if you want to use the on-chip RC oscillator and free up a couple of GPIO lines.

It turns out that ST uses a different set of tools for the STM8 than their STM32F chips. I use the instructions from STM8 software for test the configuration.

After quite a bit of struggling, I have finally managed to run ST Visual Programmer from ST Toolset.

I don't think the tool should read back all '0', but then again I have not supplied any of the programming files. Changed a few bytes and it seems to program and verified fine. That's all I can do for now.