C-BOARD (DSP-Board) for UV-K5 (Updated June 9, 2024)

 

C-BOARD for UV-K5

I created an externally mountable DSP-Board to process digital signals from UV-K5.

DSP-Board was named C-Board. C-Board is divided into versions ranging from the simplest version to one that can be equipped with GPS.

Version history of this document

  - If the C-Board does not operate due to insufficient current, UV-K5 modification  

  - gps schematic update

0.About C-Board

To apply the DSP-Board to UV-K5, we first implemented a high-speed communication protocol. The videos below use the protocol.

0.1 RP2040 board I used #1

This is the cheapest board. It's usually around $1.4 and sometimes sells for less than that during discounts.

Below is my order details. About a month ago, the product was on sale, so I bought 3 for $1.18

The components are mounted on both sides of the PCB, so they are a bit difficult to attach.

This is also the RP2040 board I use.

Since there are no components on one side of the PCB, the C-Board can be made a little thinner.

The C-Board created in this article uses this board. It can be made in the smallest size as shown in the picture below.

1.Basic Version

  It performs all DSP-related functions, but you cannot hear sound.

(Recommended)

The UV-K5's audio signal comes out at close to 8Volts when the volume is maximized. The ADC input range of RP2040 used in Raspberry pi PICO is 0~3.3Volt.

You can use it by reducing the volume appropriately.

I don't know if the ADC bypasses excess current, but no major problems occurred even when the volume was set to maximum.

(Not recommended, but the circuit I use)

2.monitoring version

A version equipped with additional speakers for monitoring and a microphone for simple communication.

Note 1: If you want to hear loudly, the bigger the speaker, the better. I got satisfactory results with speakers about 1cm wide.

Note 2 :  The resistor connected to the speaker must be capable of transmitting high current. I use five100 ohm resistors connected in parallel as shown below.

3.GPS Version

3.1 When using low-power GPS (no modification required for UV-K5)

I used the GP02-Kit, and this product can use the 3.3V of the C-Board.

The widths of the GP-02 Kit GPS and RP-2040 Board are the same.

When GPS was first installed on UV-K5 a few months ago, it was possible to fold the GPS.

However, as a result of testing, there is no major problem even if installed as shown below.

When updating the firmware of the C-Board, you must press the Boot switch mounted on the RP2040 board below. It is difficult to press the button when equipped with GPS.

It is also a good idea to extend and install the SW. It depends on your idea.

For reference, I simply placed paper between the switch and the GPS.

When you press the GPS button with force from above, the Boot switch is pressed.

3.2 How to use a separate power source (UV-K5 modification required)

Even if 3.3Volt is supported, it is difficult to use simultaneously due to excessive power consumption of GPS.

Therefore, a separate power supply unit must be added

Note 1 : Most GPS are equipped with a regulator that converts 5.0 Volt to 3.3 Volt.

All four types of GPS I have are equipped the same way. 

When replacing the 5.0 -> 3.3 converter mounted on the GPS with a general 3.3 regulator, the lm1117 5.0 part of the above circuit can be omitted. (general 3.3 regulator support 8.4 volt input)

In the picture below, the component in the square box is a 5 Volt To 3.3Volt regulator.

I took 8.4Volt from the point indicated by the arrow in the picture below.

4.Tip

4.1 You can make it by cutting the headset or programming cable.

If you purchase the cable below, you can get two plug parts.  However, most plugs have only three wires connected. You have to cut the plug with a knife and solder all the wires together. It's not an easy task.

A version made with the same plug as above.

4.2 use 3.5mm and 2.5mm plug

I have recently purchased and made a plug like the one below.

To ensure the correct location and direction of the plug, insert the plug into the radio and mark its location.

Basic version

Monitorring versoin

I cut the plastic and made it into a case. If you or someone around you uses a 3D printer, you can make a cooler case.

Installed

5. Use of UV-K5 and C-Board

5.1firmware upload

1.While holding down the Boot button, connect the USB to the computer.

2.A removable disk called RPI-RP2 will appear on your computer.

3.Copy the firmware file and paste it into the RPI-RP2 disk.

The firmware is currently under development and will be distributed together with the release of UV-K5 firmware CEC versin 0.4.

If you need firmware even before Version 0.4 is released, we will send it to you by email.

(No additional equipment is required to upload firmware to the C-Board.)

SSB Receive TEST

Receive FT8 and Decode using UV-K5 with C-Board (Standalone )

5.2 When C-Board does not work

 - Some UV-K5 devices have current limitations, so the C-Board may not operate.

 - In some cases, the C-Board works, but only when entering FT-8 mode.

   This also means that the current supplied to the C-Board is insufficient. When operating in FT8 mode, more current is required due to overclocking.

 - The C-Board operates normally, but when connected to GPS, it does not work.

I tested a total of 8 UV-K5s and had problems with 2 of them. This issue was reported by a beta tester a month ago.

Resolution

1. Connect a resistor of 2 to 5 ohms to part A in the picture below.

  (I connected 3 ohms (3 10 ohm parallel))

  Most problems will probably be solved by simply adding a resistor to point A.

2.If the problem is not resolved yet, install a 10 ohm resistor at point B. (This part is mostly unnecessary)

In my case, one UV-K5 had to be modified at both points A and B to use the C-Board with GPS.

   

Example (My Case)

I removed the original 47 ohm resistor at point A for testing, but you don't need to. (2~5 ohm resistors are connected in parallel, so the 47 ohm resistor will be ignored)