SPE EXPERT remote control console with ESP32 'CYD'

Project presentation

SPE Expert linear amplifiers front panel membrane keyboards do not have an infinite lifetime, as the plastic foil of keys can become worn out or their contacts can be 'sticking' after some time.... so it's best to avoid using them too frequently. 

Therefore I have been using the SPE  remote control software running on PC for some years. There are some software alternatives published on the web, with even more 'compact' interface, but still this requests  an extra window on your crowded desktop.   As alternative I was looking for some simple and convenient control possibility on the desk, at the touch of fingers ... very handy for example to check signal while swapping antenna's. No need to readout the data like power, voltage, current, SWR, etc ... these can be scrutinized from the LCD display - it was never the intention to provide a full function remote function.

First wanted to try with ELGATO Streamdeck miniconsole, a nice toy where you can program buttons and assign functions, maybe from there something could be developed towards the Expert. Unfortunately, my Windows 7 'shack PC' was not compliant to run the Streamdeck drivers ... so had to think of another solution.

ESP32 Cheap Yellow Display (CYD) development

A very interesting µcontroller board is the ESP32 CYD. It is based on ESP32WROOM, has a TFT display 2,8" 320x240 pixels, a tactile touch pad, on board audio amplifier, WiFi, LDR, ... all in one assembly, at very reasonable cost (less than 15,-EUR !). And it can be integrated in a small 3D printed console, there are several projects freely downloadable on the Web.

In the end, the project resulted in a small remote control console :

Following functions have been provided:

• Extremely compact control with small footprint on the desktop. Connection to the SPE & power supply by one single cable.

• Communication with SPE over the RS-232 serial port. Attention : as mentioned in the manual, if the USB port is connected to a PC, this serial port of SPE is not active. On the ESP32 side, a dedicated UART port is used (not the same port as the USB port, this is reserved for flashing firmware and debugging) As the communication protocol is identical for all 'LDMOS based' and the 2.0k SPE amps, the console can be used with any of these amplifiers (tested OK on 1.3k and 1.5k TAURUS). NOTE: it is NOT compatible with the 1.0K type. The communication protocol supported is detailed in this manual.

• Remote control of 6 most important functions : power (ON & OFF), ANT selection , OPR/STBY selection, DISPLAY selection, RF POWER OUT selection, TUNE initiate

• Toggling between OPR and STBY seems not always taken into account by the Expert, as well when issued from the SPE software. Therefore, the console detects if status is effectively changed, if not, will re-issue the command.

• These functions can be called only in an 'intelligent' manner : for example, you cannot change antenna during TX, initiate a TUNE while in OPR mode (corresponding buttons are grayed out)

• Audio feedback of keypresses and alarms by beeper

• Actual and instantaneous display of status : Antenna chosen, RX or TX,  RF POWER level, ALARM

• A SETTINGS page is provided, allowing to select (settings are memorized):

  • the baudrate for communication with the PA (115k2 bd is default, 19k2 bd optional), A lower baudrate could be useful for 'noisy'  environment,   but response is somewhat more sluggish. I am running on 115k2 on a 3m long cable without any problems ... and no RFI at all, on any band.

  • the POWER UP function :   provided by putting a control line to +12V.  For switching  'OFF', this line goes low and a command is as well issued to PA.

  • the SLEEP function : if enabled and the SPE is not powered-up, the console will first go to SLEEP mode, then after a while to DEEP SLEEP mode. This to conserve power and avoid any 'clutter' on the desk: if full light, the consumption is about 200mA (250mA when WiFi active), less than 40 mA in DEEP SLEEP. When screen is touched or SPE comes on-line, the console wakes up automatically.

• The on board LDR adjusts the screen backlight in function of ambient light conditions.

• Firmware updates by OTA (see below) - no need to open the case or connect any cable to update !

Some screenshots

Firmware upload & updating

ATTENTION : the firmware has been written for following board , here are the important parameters, as several versions exist: on the market:

Check documentation of your candidate board !

• ESP32WROOM 'Cheap Yellow Display' (CYD) /  4MB Flash memory

• Maker 'Jingcai Intelligent' (Other brands might be OK as well, as long as all critical parameters OK)

• Type : ESP32-2432S028R  (the 'R' is important !)

• Model revision : 1.2

• Screen : TFT 2.8" diagonal  320x240 pixels / driver chip ILI9341

• Touchpad : Resistive / controller XPT2046

• GPIO 22, 27 and 35 on external connectors (these are the I/O ports normally provided, but some boards seem to have 33 instead of 35)

• LDR input is GPIO 34

• Backlight is GPIO 21

• Speaker is GPIO 26

• Dimensions : 86 x 50 mm

• Price about 15,-EUR (maximum) - I have seen them @ Ali less than 3,-EUR !

As all the 'bits and bytes' on board of the CYD must collaborate in the proper manner, and in order to avoid any issues during the upload of the firmware into a blank ESP32 board, I have made a 'package' of all files, which can be uploaded very easily - without any knowledge about microcontrollers, without any software to install - as a simple batch job, which will even smoothly run from a Win7 32bit PC. This is done by connecting the CYD to your PC via a USB cable, identifying which (virtual) COM port is created, entering the port number in the batch routine when asked for it, and that's all !

Once the CYD has been loaded with the required console system files, the software updates can be performed by OTA ('Over The Air'). When the function is active, the console switches on it's WiFi, configured as access point.  You connect with your laptop to SSID 'SPE-console' (no need for a WEP key), you browse to the indicated webpage (console will deliver you an ip-address automatically) and from there you select the new firmware file and start the upload - done in 10 seconds ! No need to open the console case, no need for cables ...

As the sketch/firmware is very dependant on some libraries which had to be custom trimmed for this project, it would be of little value to publish the sketch code without all underlying specific mods, and thereby not offering any guarantee that it will still be functional with possible future evolutions of  these libraries and/or development tools. Therefore I have decided not to release the coding, but instead take a complete 'snapshot' of a working system, which will work 100% for sure if installed on same flavor of hardware.

DOWNLOAD the file package as a zip file (about 4MB).

Unzip in some folder you created, and double click on the file "=spe-console-loader.bat" ,  then follow instructions to start the initial upload procedure. Don't forget to depress the BOOT button on the CYD to initiate this upload process, once running, it can be released.

Latest firmware version is V1.15, you can download it here. This file can be uploaded by the OTA procedure.

Another (more complex) method for the initial upload is by using a web facility like https://esptool.spacehuhn.com/

The 4 files below can be uploaded in one run, after selecting the right COM port and depressing the BOOT button. Attention: not all browsers will support serial transfer, see the docs of the webtool (Hint: Chrome will do)

3D printed case

A suitable extremely compact case can be found on Thingiverse https://www.thingiverse.com/thing:6918515.

It was designed for a touchscreen with about same dimensions as the CYD, but the front frame will need some adjustments (milling out somewhat with DREMEL took) to allow passage of connectors. The CYD mounting holes will as well have to be filed out to allow mounting with small self tapping screws. Furthermore, in the frront panel a 3mm hole must be drilled above the LDR to allow light to shine on it, once drilled it can be neatly finished with the front part of a 3mm LED (clear translucent type, for example white color) kept  in place by a droplet of super glue. 

Download STL files here, should it be off-line on Thingiverse.(zipped, about 11 MB).. An adapted version, without need for adjustments, is presently under design ...

Despite being extremely compact, this case offers enough space to integrate the 5V voltage regulator, beeper and RS-232 to TTL converter.

Another design, however less compact is https://www.thingiverse.com/thing:6910220 . There is a file version with no hole on top of main cabinet. I have adapted the front frame to delete the slot on the side you can download it here.  

Schematic diagram

The schematic diagram has been hand-drawn, as it is extremely simple ...

Click to download full size PDF

Other bits and pieces required / Wiring to SPE

Some information about other parts/components required :

• RS-232 to TTL converter : I found a tiny PCB fitted with MAX3232 IC, only 15mm long. Attention : the ESP32 I/O lines are not at TTL level but 3,3V. (The MAX3232 can convert this level to RS-232) .  

• Buzzer : it is a miniature PIEZO buzzer (not the MAGNETIC type), The type I found was a 'self-beeper' (active type) with supply from 3 to 12V and nominal frequency of 4,3 kHz. When I measured it's frequency, it was sounding at 4,6 KHz, so I set the audio output frequency at this value. Probably a non 'self-beeping' type (passive) will work as well. Polarity has no importance, the speaker output of CYD is differential (audio amplifier chip is SC8002B).

• 2 SUB-D male connectors are required, one 9 and one 15 pin. Take good quality, with metal covers.

• Optocoupler 4N35 or similar to provide +12V to SPE 'power up' input

• Voltage regulator µA7805 on small heatsink

• Connectors are 'MICRO JST 1,25mm'  female, 3 pcs 4 pin, 1 pce 2 pin. You will easily find them with pigtails attached, approx 20 cm long. Sometimes these are called 'MOLEX MICROBLADE'.

For the wiring to SPE EXPERT, I used a (globally) shielded flexible cable with 4 cores. The shield will conduct the -12V (GND), one core the +12V supply,  two cores the RS-232 in/out, one core the +12V to power up SPE.  This cable runs into the DB9 going into the PORT socket of SPE, inside the DB9 it splits into a power supply cable an a small cable running towards the DB15 plugged into the second CAT socket (I only use one TRX). Should you run 2 TRX, you can arrange wiring to one of the two CAT ports.  Note : as some ports of SPE Expert are delivering +12V when the SPE is powered up, it is possible to power the console from there ... but in this case you will not be able to power up the SPE from the console.

RFI interference

On the cable between console and SPE, at the SPE end close to the DB9 connector, I put a ferrite clamp-on core. On all bands, and at all power levels, I have never observed any erratic behavior of console or SPE during transmissions. 

IMPORTANT: Please note that the software & device concept is presented 'as is' with no guarantees whatsoever and can be used free of license cost by individual  HAMs, but not  used for any commercial purpose, as the intellectual property remains entirely by the author.