Picon Zero on the Pi with NodeJS

RE: Picon Zero on the Pi with NodeJS

Workshopshed — Sun, 30 Jul 2017 08:43:19 GMT

For the motor test, I swapped the power to come from the external USB. Even with that configured I could not get motion from my old motor. I swapped to a motor that I'd created by modifying a micro-servo[View:/resized-image/__size/16x16/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-6c701268-da9a-4670-98fe-410b5e9d0958/contentimage_5F00_6666.png:16:16] and that worked fine. I'll try my other test motor and some bigger motors via the external power supply connectors.

[View:https://players.brightcove.net/1362235890001/NkxiVJdjx_default/index.html?videoId=5525939503001:740:466]

To modify a servo for continual rotation there are a couple of changes needed. Firstly you'll need to either strip out the electronics, if you want to control the speed externally or to fit a resistor you want constant speed. Then there is a small tab on the gears that acts as a mechanical stop. That needs cutting off. Have a look on Instructables for many different examples of how to do that.

RE: Picon Zero on the Pi with NodeJS

Workshopshed — Sun, 30 Jul 2017 08:31:34 GMT

Tested the I/O and there seems to be an intermittent issue with the analogue input. It's supposed to return values from 0-1023 but sometimes it just jumps to an arbitrary large number.

Also I've had an error on the read

Error reading length of bytes

at i2c.readBytes (/home/pi/node_modules/i2c/lib/i2c.coffee:83:10)

It should be able to put in an error detection and retry mechanism for these two. I'd be surprised if this did not also occur with the Python library, that has a retry mechanism but not an error detection.

[View:/resized-image/__size/342x266/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-6c701268-da9a-4670-98fe-410b5e9d0958/3364.contentimage_5F00_184856.jpg:342:266]

The PWM output is ok but seems a little flickery at low percentages. I've seen that with other solutions though.

The servo seems to work just fine but the comment in the code said -100 to + 100 where as it seems to be 0 to 180 degrees.

RE: Picon Zero on the Pi with NodeJS

Workshopshed — Tue, 25 Jul 2017 10:28:23 GMT

I tested the Digital I/O using an RGB LED, that seems to be working fine.

[View:https://players.brightcove.net/1362235890001/NkxiVJdjx_default/index.html?videoId=5520620216001:740:466]

RE: Picon Zero on the Pi with NodeJS

mconners — Wed, 19 Jul 2017 12:44:18 GMT

Nice [mention:4236e66f810f492faa977aafb3ee70a6:e9ed411860ed4f2ba0265705b8793d05]. Neat stuff.

Mike

RE: Picon Zero on the Pi with NodeJS

DAB — Tue, 18 Jul 2017 18:25:49 GMT

Nice post Andy,

The board looks interesting and it looks like the control over I2C well supported.

DAB