The second plug panel has arrived. I’ll document my test results in the coming days.
First, the Analog Plug – an 8-channel 12-bit ADC connected via I2C:
It’s based on the ADS7828 chip. Here’s a demo sketch to read it out:
I hooked it up using various gimmicks lying around here – this ties a trim pot to channel 4, with range 0 .. 3.3V on the wiper:
As you can see, the Breadboard Connector can be used to hook up to 8 of the 12 pins of this plug.
Here’s some sample output:
I slowly turned the wiper as you can see. It stops at 4095 counts, which represents the 2.5V of its internal reference. Appears to work fine in this test setup at the maximum I2C rate, somewhere over 1 MHz. The readings didn’t change by more than one count when touching various parts of the circuit, so as first impression it looks like it’s pretty stable.
This plug has two solder jumpers, to configure its I2C address to 0×48 .. 0x4B, which in hindsight is a bit overkill. Only minor nit is that I mis-labeled the A0 jumper – as shown in the picture, the address ends up being 0×49 i.s.o. 0×48. Oh well, a small silkscreen fix will resolve that later.
So there you have it – eight 3.5 digit voltmeters on one tiny blue-and-gold plug :)