7 replies to this topic

[ByteMaster]

What connections are necessary between the GO!Bus and the STM8 to reflash the module similar to the STM32?

[Matt Isenhower]

Hi Kevin, This wiki page details most of the hardware/electrical requirements for STM8S-based modules: http://wiki.netduino...ders-Guide.ashx Pin 4 should be connected to SWIM and pin 5 should be connected to NRST. The wiki pages for the potentiometer and RGB LED modules have Eagle schematics attached in the top right corner, and you can pretty much follow the schematics for those modules as a base for custom modules. Matt

[ByteMaster]

Thanks Matt -

This wiki page details most of the hardware/electrical requirements for STM8S-based modules:
http://wiki.netduino...ders-Guide.ashx

This looks like a great asset!

Pin 4 should be connected to SWIM and pin 5 should be connected to NRST

We probably have to assume that those lines are not Hi-Z, so durring development with the ST-Link2 attached, they should be disconnected? I guess a good approach would be cutting those lines in the 10 pin ribbon cable.

Kevin...

[CW2]

ST-LINK/V2 works correctly when the module is connected to the mainboard, there is no need to cut the cable (I often have ST-LINK/V2 connected through a different socket, wires directly plugged into the IDC cable header, I call it "a poor-man's SWIM adapter"). Technically, the SWIM programming requires only the SWIM pin to be connected, but with the reset wire (NRST) we allow the module to use the SWIM pin as general purpose I/O (configured via SWD bit in the CFG_GCR register).

[ByteMaster]

I often have ST-LINK/V2 connected through a different socket, wires directly plugged into the IDC cable header, I call it "a poor-man's SWIM adapter"

CW2 - Got-it...pretty cool!

Using a different socket, I assume you couldn't have another STM8 on the same side of the GO!BUS, correct? Or unless I'm missing something, you would end up programming two devices or at least get some serious issues with both chips on the SWIM line.

Hmmm...I'll bet you could also use the break out board that I'm using to connect to the logic analyzer, between the main board and the module, and hookup the ST-Link V2 up to that. This would allow us to leave the programming connector off our module! Way kewl!

Might be worth it to get some boards made up similar to...

...but with a socket to plug in the ST-Link V2. Would be a really good way to do development. All sorts of pins to connect a logic analyzer as well as program the device. In this case, you wouldn't tie those lines back to the main board and could have multiple STM8's without having to worry about bus contention.

Great H/W design here on the GO!Bus!!!

Kevin...

[CW2]

Using a different socket, I assume you couldn't have another STM8 on the same side of the GO!BUS, correct? Or unless I'm missing something, you would end up programming two devices

Yes, you are right, it is recommended to have only one module connected on the same go!bus for programming. It is not necessary to physically disconnect the other module cables, the mainboard can simply turn off their power.

[Matt Isenhower]

ST-LINK/V2 works correctly when the module is connected to the mainboard, there is no need to cut the cable (I often have ST-LINK/V2 connected through a different socket, wires directly plugged into the IDC cable header, I call it "a poor-man's SWIM adapter").

I understand this works, but is this actually a good practice? Are the programming lines actually configured in a hiz/weak pull-up mode when idle?

[Chris Walker]

When we debug STM8S modules while they're connected to the go!bus, we typically wire up two socket adapters...and then connect all the lines between them except the SWIM lines. That way we can debug that module--and others--at the same time, and there's no need to worry about anything else. The mainboard may put the UART pins in "input, pullup" mode during runtime. That may be okay with SWIM, as long as the high/low transitions don't become sloppy due to the weak pullup. Chris