4.4 In-Circuit Serial Programming (ICSP) Pins

The ICSPCLK and ICSPDAT pins are used for ICSP and debugging purposes. It is recommended to keep the trace length between the ICSP connector and the ICSP pins on the device as short as possible. If the ICSP connector is expected to experience an ESD event, a series resistor is recommended, with the value in the range of a few tens of ohms, not to exceed 100Ω.

Pull-up resistors, series diodes and capacitors on the ICSPCLK and ICSPDAT pins are not recommended as they can interfere with the programmer/debugger communications to the device. If such discrete components are an application requirement, they need to be removed from the circuit during programming and debugging. Alternatively, refer to the AC/DC characteristics and timing requirements information in the respective device Flash programming specification for information on capacitive loading limits as well as pin input voltage high (VIH) and input low (VIL) requirements.

For device emulation, ensure that the “Communication Channel Select” pins (i.e., ICSPCLK/ICSPDAT) programmed into the device match the physical connections for the ICSP to the Microchip debugger/emulator tool.