The PIC16F1459 has a pin called VUSB3V3. An internal LDO generates 3.3V for use with USB. An external capacitor of 0.47uF should be placed between this pin and ground.
When I initially populated my board, and tried to get something going quickly, I thought this would only be necessary once I started using USB. However, without this, PICkit3 sees an ID of zero and fails to program the chip. Various web pages mention that an ID of zero usually means power issues, and sure enough, when I populated this capacitor, PICkit3 started seeing the correct ID.
After getting the correct ID, I also had to remove the 100Ω resistors on the PGC/PGD paths to actually get programming going. Some sample circuits have these for protection, but others say to avoid these.
When I initially populated my board, and tried to get something going quickly, I thought this would only be necessary once I started using USB. However, without this, PICkit3 sees an ID of zero and fails to program the chip. Various web pages mention that an ID of zero usually means power issues, and sure enough, when I populated this capacitor, PICkit3 started seeing the correct ID.
After getting the correct ID, I also had to remove the 100Ω resistors on the PGC/PGD paths to actually get programming going. Some sample circuits have these for protection, but others say to avoid these.
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