4.5.4 Connecting to External Microcontrollers

The figure and table below show where to connect the programming and debugging signals to program and debug external microcontrollers. The on-board debugger can supply power to the external hardware or use an external voltage as a reference for its level shifters. Read more about the power supply in 4.3 Power Supply.

The on-board debugger and level shifters actively drive data and clock signals used for programming and debugging (DBG0, DBG1, and DBG2). Pull-down resistors are required on the ICSP™ data and clock signals to debug PIC® microcontrollers. All other interfaces are functional with or without pull-up or pull-down resistors.

DBG3 is an open-drain connection and requires a pull-up resistor to function.

PIC16F17146 Curiosity Nano has pull-down resistors R204 and R205 connected to the ICSP data and clock signal (DBG0 and DBG1). There is also a pull-up resistor R200 connected to the MCLR signal (DBG3). The location of pull resistors is shown in 8.2 Assembly Drawing in the appendix.

Remember:
  • Connect GND and VTG to the external microcontroller
  • Tie the VOFF pin to GND if the external hardware has a power supply
  • Make sure there are pull-down resistors on the ICSP data and clock signals (DBG0 and DBG1) to support the debugging of PIC microcontrollers
Figure 4-10. Curiosity Nano Standard Pinout
Table 4-4. Programming and Debugging Interfaces
Curiosity Nano PinUPDIICSP™SWD
DBG0UPDIDATASWDIO
DBG1—CLKSWCLK
DBG2———
DBG3—MCLRRESET