Firmware Upgrade

The RS-UV3A firmware can be updated using a built-in bootloader. This guide covers the upgrade process.

Prerequisites

You’ll need:

1. RS-UV3A connected via USB or serial
2. Windows PC (bootloader software is Windows-only)
3. mikroBootloader 2.3 software
4. Latest firmware file (.HEX format) from HobbyPCB

Getting the Software

Bootloader Software

Search for and download mikroBootloader2.3.zip. This is a standalone tool from MikroElektronika that doesn’t require installation.

Firmware File

Download the latest RS_UV3_FIRMWARE_VX-X.HEX from the HobbyPCB Files page.

Upgrade Process

Step 1: Configure the Bootloader

1. Extract and run mikroBootloader.exe
2. Click Change Settings
3. Set Port to your RS-UV3A’s COM port
4. Set Baud rate to 115200
5. Leave other settings at defaults
6. Click OK

Finding Your COM Port

On Windows, check Device Manager → Ports (COM & LPT) to find the RS-UV3A.

Step 2: Enter Bootloader Mode

The RS-UV3A must be listening for the bootloader before you can connect.

Method 1: BL Command (Normal Operation)

If your RS-UV3A is working and responsive:

1. Open a terminal program (PuTTY, Tera Term)
2. Connect at 19200 baud
3. Send the command:

   BL

4. Close the terminal program (important!)

The RS-UV3A is now waiting for the bootloader. It will wait indefinitely.

Method 2: ICSP Jumper (If Unresponsive)

If the RS-UV3A won’t respond to commands (corrupted firmware):

1. Power off the RS-UV3A
2. Place a jumper on the ICSP header:
   • Pins 1-2 for USB/JP1 serial upload
   • Pins 4-5 for DE-9 serial upload
3. Power on the RS-UV3A

The RS-UV3A will boot directly into bootloader mode.

Step 3: Connect and Upload

1. Ensure your terminal program is closed
2. In mikroBootloader, ensure PIC18 is selected in “Select MCU”
3. Click Connect
4. You should see “Connected” in the History window
5. Click Browse and select the firmware .HEX file
6. Click Begin uploading
7. Wait for the upload to complete (progress bar fills)

Step 4: Restart

1. Power cycle the RS-UV3A
2. Connect with a terminal program
3. Verify the new version:

   FW

You should see the new firmware version reported.

Troubleshooting

”No response from device”

• Verify the COM port is correct
• Ensure the terminal program is closed
• Check that you sent BL command successfully
• Try the ICSP jumper method

Upload Fails Partway

• Check USB cable connection
• Try a different USB port
• Reduce cable length
• Ensure stable power supply

RS-UV3A Unresponsive After Failed Upload

Use the ICSP jumper method to force bootloader mode, then re-upload.

Wrong Bootloader Baud Rate

The bootloader always runs at 115200 baud, regardless of the B1 setting. Don’t confuse this with the normal operating baud rate (default 19200).

After Upgrading

After a successful upgrade:

1. Check version: FW
2. Your saved settings should be retained
3. If settings were lost, restore defaults: FD1
4. Reconfigure as needed
5. Save settings: ST0

Version History

Check the HobbyPCB wiki for release notes on each firmware version. Typical improvements include:

• New commands
• Bug fixes
• Improved receiver performance
• Additional features

Important Notes

Don’t Interrupt the Upload

Never power off or disconnect during the upload process. This can leave the RS-UV3A in an unresponsive state requiring the ICSP jumper recovery method.

Windows Only

The mikroBootloader software only runs on Windows. For Linux/Mac users, a Windows VM or separate Windows PC is required for firmware updates.

Exiting Bootloader Mode Without Uploading

If you accidentally entered bootloader mode (BL command) and want to exit without uploading:

• Simply power cycle the RS-UV3A
• It will boot normally (unless you have an ICSP jumper installed)

ICSP Header Pinout

For reference, the ICSP header pins (when viewed from the top):

   1 2
   3 4
   5 6

• Pins 1-2 jumper: Bootloader on USB/JP1 serial
• Pins 4-5 jumper: Bootloader on DE-9 serial

Remove the jumper after successful upload to resume normal operation.