I've just had my first batch of PCB prototypes delivered from the manufacturer, and when I went to program them, the target voltage is reading too low. The device is based around an Atmel SAM L21 MCU, and I've attached a schematic for reference. The power supply is 3 AA batteries in series, connected to a Microchip MCP1711 3.3 LDO voltage regulator. In Atmel Studio, when I try to read the target voltage, it reads either 0.2v or 0.3v. I assume that because there is a voltage being read, that power is reaching the board, but I'm not sure why it's reading so low.
Does anyone have any suggestions as to what might be the problem? I've tested the batteries and the reading between them is reading around 4.5v, as it should be. Could this be a problem with the Atmel ICE programmer?
Any suggestions would be great. Thanks guys!
Best Answer
It seems like you have used altium for you circuit. Usually the designators are used as numbers and the description of the pins is the description. As you currently did it, it is unclear wheter it is a net name or the designator of the pin.
Assuming from your comments, it is the pin designator, in which case you forgot to connect the ground of the battery to the rest of the circuit. As well as one of the ground pins of your microcontroller.
As a reference for you next circuit, this is the conventional way in altium to make your pin designators: It helps preventing confusion between net labels and pin designators.