UBITX.NET RECOMMENDED MOD
A colour touch screen can easily be added to your µBITx and adds great additional functionality and ease of use, while also turning your rig into a state of the art appliance. uBITx.net recommends using the Nextion screen in conjunction with KD8CEC firmware for both Nextion and Raduino processors. Firmware versions are already available to support 2.4″, 2.8″, 3.2″ and 3.5″ Nextion displays. If you are replacing the standard display, you will need a 3.2″ or larger display to cover the hole left by the 16×2 display.
The photo above shows the touch panel display mounted on the front panel of the µBITx built by Mike ZL1AXG . Pressing on the screen will perform functions like changing band (up/down), changing frequency, adjusting the Attenuator (ATT), changing IF Shift and RIT, and entering Split mode.
See Ian’s webpage for details about downloading the various firmware options along with his detailed instructions.
You will need:
- A Nextion screen (3.2″ or larger recommended)
- 4 pin connecting cable to connect the screen to the Raduino’s pins (+5v, ground, serial data in, serial data out). You can use female to female jumpers.
- Test the Nextion works by using the USB adapter provided. Using the supplied cable, connect the +5v and ground connections to the correct pins on the USB adapter. Take care with polarity as reversal will destroy your Nextion display. Use a USB cable to power up the Nextion. It comes with firmware installed for testing purposes.
- Cut out the hole for your Nextion display on your front panel. Take special care with measurements and fit carefully so that the hole is no larger than the grey line around the outside of the visible area of the screen.
- Install the latest update for the KD8CEC firmware for your Raduino.
- Download the latest stable (or Beta) firmware for your Nextion display from the www.hamskey.com website. This must match your display size and type (Basic/Enhanced). A basic display is adequate. The Enhanced version has a Real Time Clock (RTC), accessible flash memory, and 8 GPIO ports. The firmware does not use these features at this point in time.
- Copy the Nextion firmware to a FAT32 formatted micro-SD card of 1GB or more in size.
- De-power the Nextion display. Install the micro-SD card containing the firmware for your screen size. Power up the Nextion display and you will see the firmware loading to ROM. When this cycle is complete de-power the Nextion.
- Install the Nextion in your uBITx, and connect up cables to the pins as described on www. hamskey.com.
- Power up the rig and it should be all go!
When installing Nextion displays:
1) The Display wants the microSD card to be formatted as FAT32. Make sure your microSD card is no larger than 32GB
The default in Windows is to format cards > 32 GB as exFAT, which the Nextion will not accept.
Currently you only need a 2 GB card, to fit the firmware.
uBITx.net suggests using an 8Gb or 16Gb card.
2) If you have a problematic microSD card, when you power up the rig you might not see anything on the display, not even a backlight !
I spent considerable time trying to solve what I thought was a wiring/power problem to the display when it was a bad SD card. When the I removed the card and power-cycled the rig the Nextion display came up fine with a demo program that was already loaded. So my recommendation is for the initial power up of the display don’t insert the SD card. That way you can be sure that you have it wired up ok before you start messing with SD cards.
3) Beware, ground and +5V connections on the Raduino going to the Nextion Display are adjacent to each other.
It is recommend that you check and recheck your wiring several times before applying power. It is very easy to accidentally swap these and you won’t be happy if you do. As they say, “An ounce of prevention is worth a pound of cure”.
4) Beware of Duplicate .tft files
You may get a message on the display that the load failed because there is more than one .tft file on the SD card. This can happen even when you look and you see only one file.
You need to be sure to enable viewing of hidden files in file explorer (Windows) or finder (on a Mac)… There’s probably one hiding there with the .tft suffix that you need to delete. I don’t think either operating system will show hidden files by default. The same goes for Linux.
5) Make sure you install the screen the right way around
Power up the display before you start making holes and check the orientation of the display and that the screen is functioning correctly. As with the 16×2 display, it is possible to install the display upside down by mistake! Given it is not symmetric (there is a wider bar to the right hand side of the display) care is needed! The inner silver line on the screen defines the touch sensitive boundary. Cut your hole so that the screen fits so the line is just visible around the outside edge.
Dimensions of Nextion displays can be found on the itead website. Click on your display and near the bottom of the page you will find a link to a template with all screen dimensions shown.
6) For most the 3.2″ or 3.5″ screen will be preferable
A 3.2″ screen is only just big enough to feel comfortable for us fat-fingered chaps. It is also only just wide enough to cover the hole left when you remove your old 16×2 screen. Smaller screens inserted in the same space will require an additional aluminium or plastic plate to be screwed to your front panel to cover up the edges of the hole left by the 16×2 screen.
7) Current draw and the Raduino’s 5v Regulator
Current draw on a 2.4″ and a 3.2″ Nextion display is around 125 ma. for a 2.8″ display and 110 ma for a 3.2″ display. The current is possibly less on the 3.2″ display because it appears to be a later design. When measured, both displays were at full brightness. The Raduino 5V regulator should be fine at these current draws. If in doubt, add a heatsink to the regulator!