PIC12F635/683, PIC16F63X/68X Limitations

PIC12F683
PIC16F636, PIC12F635
PIC16F639
PIC16F684
PIC16F688

Headers are required for debugging when using these devices. See the “Processor Extension Pak and Debug Header Specification” for details. Header limitations are as follows:

  • General Debug Limitations
  • General Programming Limitations
  • General Device-ME2/ICE/ICD Limitations
  • You cannot single step through an interrupt. Due to hardware restrictions, the debugger or emulator cannot jump to the interrupt vector memory location in Single Step mode.
  • Cannot erase ID memory at Vdd < 4.5 V. At Vdd < 4.5 V, the part cannot be bulk erased, so it has to be row erased. Row erase can be used on program memory, but not on configuration memory (where user ID resides).
  • Program memory standard Flash. Program memory not enhanced Flash. You cannot program in Low Voltage mode (Vdd < 4.5 V). See the device programming specification for more information.

PIC16F636 Family Only

  • Above 16 MHz, in External Clock input (EC) mode, an MPLAB IDE Reset executes the first few instructions instead of only one instruction. The workaround is to add three No Operation (NOPs) at the reset vector.

PIC16F684-ICD Only

  • Cannot communicate with an AC162055 below 3.375 V and cannot erase USER ID below 4.5 V. You can program and debug at 2.0 V if you start with an erased header (erased at a higher voltage).

Freeze on Halt Limitations

  • Timer0 will not freeze using the internal clock.
  • CMOUTx pins do not freeze, status bits and interrupt flags do freeze.
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