ICSP Programming

The RS-UV3A includes a 6-pin In-Circuit Serial Programming (ICSP) header for programming the PIC microcontroller. This header serves two purposes:

1. Bootloader forcing — Jumper pins to force bootloader mode on startup (for firmware updates when the board is unresponsive)
2. Direct ICSP programming — Connect a PICkit or similar programmer to flash firmware directly

For routine firmware updates using the bootloader, see the Firmware Upgrade guide.

ICSP Header Location

The ICSP header is a 6-pin (3×2) header located near the PIC microcontroller (U2) on the left side of the board. The pins are staggered — offset from the standard 0.1” grid — to allow a programming clip or individual test probes to make contact without soldering a header.

Staggered Pins

The staggered design means you can press a standard 2×3 pin header into the holes and it will friction-fit for programming. No soldering required.

ICSP Header Pinout

Viewed from the top of the board:

   1   2
   ●   ●
   3   4
   ●   ●
   5   6
   ●   ●

Pin	Signal	Description
1	Boot Select A	Jumper to pin 2 forces USB/JP1 bootloader on startup
2	VDD (+3.3V)	PIC supply voltage
3	PGD	Programming data (PIC RB7, pin 17)
4	PGC	Programming clock (PIC RB6, pin 16)
5	GND	Ground
6	Boot Select B	Jumper to pin 5 forces DE-9 bootloader on startup

Method 1: Bootloader Forcing (Jumper)

If your RS-UV3A is unresponsive (bad firmware upload, corrupted flash), you can force it into bootloader mode on power-up:

USB / JP1 Serial Upload

1. Power off the RS-UV3A
2. Place a jumper across pins 1–2
3. Power on — the board enters bootloader mode on USB/JP1
4. Upload firmware using mikroBootloader at 115200 baud
5. Power off and remove the jumper
6. Power on — normal operation resumes

DE-9 Serial Upload

1. Power off the RS-UV3A
2. Place a jumper across pins 5–6 (or 4–5, verify against your board revision)
3. Power on — the board enters bootloader mode on DE-9
4. Upload firmware using mikroBootloader at 115200 baud
5. Power off and remove the jumper
6. Power on — normal operation resumes

Remove the Jumper

Always remove the bootloader jumper after programming. If left in place, the RS-UV3A will enter bootloader mode every time it powers on instead of running normally.

For the full bootloader upload process, see Firmware Upgrade.

Method 2: Direct ICSP Programming (PICkit)

For advanced users who need to flash the PIC microcontroller directly — for example, to restore a corrupted bootloader or flash custom firmware.

What You Need

Item	Notes
PICkit 3, 4, or 5	Microchip in-circuit programmer/debugger
MPLAB X IDE	Free download from microchip.com
Firmware .HEX file	From HobbyPCB or compiled from source
2×3 pin header (optional)	Press-fit into staggered ICSP holes

PICkit Connection

The PICkit programmer needs five signals. Connect to the ICSP header as follows:

PICkit Pin	Signal	ICSP Header
1	MCLR/VPP	See note below
2	VDD	Pin 2
3	VSS (GND)	Pin 5
4	PGD (ICSPDAT)	Pin 3
5	PGC (ICSPCLK)	Pin 4

MCLR Connection

The ICSP header may not break out the ~MCLR signal (PIC pin 18) directly. Check your board revision’s schematic on the Schematics page. If MCLR is not on the header, you may need to connect the PICkit’s MCLR line directly to PIC pin 18 or the ~MCLR trace on the board.

MPLAB X Configuration

1. Open MPLAB X IDE
2. Create a standalone project or open the firmware project
3. Select the target device: PIC18F46J11
4. Select the programmer tool: PICkit 3 (or 4/5)
5. Under Project Properties → PICkit:
   • Set Power to not supply voltage from PICkit (the RS-UV3A has its own 3.3V regulator)
   • Set Voltage Level to 3.3V if powering from PICkit

Voltage Warning

The PIC18F46J11 is a 3.3V device. Never apply 5V to the programming pins. If using the PICkit to supply power, ensure it is set to 3.3V output. Applying 5V will damage the microcontroller.

Programming Steps

1. Connect the PICkit to the ICSP header
2. Power the RS-UV3A (or enable PICkit power at 3.3V)
3. In MPLAB X, click Make and Program Device (or use ipecmd for command-line)
4. Verify the programming completed successfully
5. Disconnect the PICkit
6. Power cycle the RS-UV3A

Command-Line Programming (IPECMD)

For automated or headless programming using Microchip’s IPECMD:

ipecmd -P18F46J11 -TPPK4 -M -F"RS_UV3_FIRMWARE.HEX" -OL

Flag	Meaning
-P18F46J11	Target PIC device
-TPPK4	Tool: PICkit 4 (use -TPPK3 for PICkit 3)
-M	Program device
-F"..."	Firmware .HEX file path
-OL	Release from reset after programming

Microcontroller Details

From the schematics, the RS-UV3A uses:

Parameter	Value
MCU	PIC18F46J11-I/PT (U2)
Package	TQFP-44
Flash	64 KB
VDD	3.3V
PGD	RB7 (pin 17)
PGC	RB6 (pin 16)
MCLR	Pin 18

PIC18F45K22 Reference in Manual

The HobbyPCB manual references the PIC18F45K22 when describing the mikroBootloader setup. However, the schematics for Rev A and Rev C both show a PIC18F46J11-I/PT. The bootloader selection in mikroBootloader may use the PIC18 family setting generically. When using MPLAB X or IPECMD for direct programming, select PIC18F46J11.

When to Use Each Method

Scenario	Method
Routine firmware update	Bootloader (BL command)
Board won’t respond to commands	Bootloader forcing (ICSP jumper)
Corrupted bootloader	Direct ICSP (PICkit)
Custom firmware development	Direct ICSP (PICkit)
Factory programming	Direct ICSP (PICkit)

Troubleshooting

PICkit Can’t Connect

• Verify PGD, PGC, VDD, GND connections
• Check that MCLR is accessible to the PICkit
• Ensure the RS-UV3A is powered at 3.3V
• Try reducing PICkit programming speed in MPLAB X

Programming Succeeds but Board Won’t Boot

• Verify the correct .HEX file was used
• Check that the bootloader region was preserved (if applicable)
• Try the bootloader jumper method as a fallback
• Ensure configuration bits are correct for the PIC18F46J11

Staggered Pins Won’t Hold Contact

• Use a press-fit 2×3 header and apply light finger pressure
• Solder a header if you program frequently
• Use a spring-loaded pogo pin adapter (e.g., Tag-Connect TC2030)