ATtiny1614 on JKTDEV.CO.UK

Debugging 921600 Baud on the ATtiny1614

Tue, 01 Sep 2026 21:29:21 +0100

Yesterday I had some time to continue debugging the C code that I had been porting from my previously developed Arduino code, which uses megaTinyCore, over to plain C using the MPLAB tools in Visual Studio Code.

As suspected, the problem turned out to be a USART register configuration issue, although it wasn’t quite the issue I had originally expected.

My first thought was that I had failed to correctly configure the GPIO line connected to the DE, or Driver Enable, pin of the RS485 transceiver, which in this case is a TI ISO1430.

PICkit 5, GCBASIC and a Logic Green Rabbit Hole

Fri, 28 Aug 2026 23:18:53 +0100

Today I managed to get a little time to test my PICkit 5 programmer with the UCMOD-0 module, mainly by porting the example code I had previously created using Arduino over to plain C using MPLAB in Visual Studio Code.

It isn’t quite working yet.

I can see the TX line flickering on the oscilloscope, and I already know that the receiver code works correctly from my previous test setup using a Raspberry Pi Pico 2 W. That narrows the problem down considerably.

Software Testing the UCMOD-0 over RS485

Thu, 20 Aug 2026 23:06:06 +0100

Today’s focus was on the software side of the UCMOD-0 ATtiny1614 module and the Isolated RS485 Building Block Board, creating a basic “Hello World” test program, configuring the ATtiny1614’s clock and brown-out settings, and testing communication over the RS485 bus.

Things went well overall. There was an issue with a jumper wire not being fully seated, which caused instability on the power rail and in turn caused the ATtiny to halt intermittently. Once that was fixed everything looked good.

Programming and Testing the UCMOD-0 with Arduino and UPDI

Wed, 19 Aug 2026 20:27:25 +0100

Today I finally got a chance to do some initial software testing with the UCMOD-0 and the Isolated RS485 Carrier Board.

Things went surprisingly well, all things considered, other than a ten-minute diversion trying to figure out why the obligatory “Hello World” LED blink sketch was failing to blink the LED on the carrier board.

Thankfully, the problem existed between the chair and keyboard — me — rather than with the hardware.

First Hardware Tests of the UCMOD-0 and RS485 Rev C

Mon, 17 Aug 2026 22:22:44 +0100

Today I received the latest revision of the Isolated RS485 Building Block Board and the first version of the ATtiny1614-based UCMOD-0 microcontroller module.

This was a particularly interesting batch because it gave me the opportunity to test not only the changes made to the RS485 board, but also the basic UCMOD concept in physical hardware for the first time.

RS485 Isolated Board Rev C

Rev C Isolated RS485 Building Block Board

Revision C of the Isolated RS485 board adds a UCMOD connector, an improved input protection circuit based around the TPS259474LRPWR eFuse, and a new DC-to-DC converter.

Tweaking the UCMOD-0 Microcontroller Module

Fri, 14 Aug 2026 22:47:45 +0100

It’s a short update today.

Today I tweaked the ATtiny1614 UCMOD design slightly. The main change was adding a jumper that allows the UPDI programmer’s power line to supply only the microcontroller, rather than powering the entire module and potentially any attached carrier board or other circuitry.

I also adjusted the three-pin UPDI socket to match the header layout used by the Adafruit UPDI Friend. The previous arrangement worked electrically, but hadn’t been laid out with the UPDI Friend’s physical header pin arrangement in mind.

Two Simple Boards for the Just Boards Range

Thu, 13 Aug 2026 23:03:50 +0100

Today I decided to design two simple PCBs for my ‘Just Boards’ range. Unlike most of my other boards, these are intended primarily for user assembly rather than PCB assembly services. They’re deliberately simple, use common components wherever possible, and should require little more than a decent soldering iron to assemble.

The bare PCBs can be ordered from manufacturers such as JLCPCB or PCBWay, while the components themselves are standard parts that can be sourced from Amazon or other electronics suppliers. The aim is to keep these boards inexpensive, accessible and easy to build without requiring solder paste, stencils, hot-air rework equipment or other specialist tools. In most cases, a soldering iron — and perhaps a little Blu Tack to hold components in place while the board is turned over — should be enough.

Expanding the Building Block Ecosystem

Tue, 11 Aug 2026 22:06:44 +0100

Today I sent the following Building Block Boards off to the fab for manufacture:

Rev A of the UCMOD-0 Microcontroller Module, an ATtiny1614-based plug-in module that can be fitted to compatible Building Block Boards to provide them with processing capability.
Rev C of the Isolated RS485 Building Block Board, which includes the revised input protection circuit as well as support for the new UCMOD interface.

I actually skipped manufacturing Rev B of the Isolated RS485 board. That revision had already been designed, but before sending it to manufacture I decided to add the UCMOD header and its associated circuitry, so the design moved directly on to Rev C.

Designing a Modular ATtiny Microcontroller Board

Tue, 04 Aug 2026 00:00:21 +0100

Today I started designing a microcontroller module as part of a larger project that I have been working on.

The first version is based on the Microchip ATtiny1614. The board should also be compatible with the ATtiny1624 and ATtiny3224 in their equivalent 14-pin packages, although there are naturally some differences in the peripherals and capabilities provided by each device.

The module connects to its carrier board through a simple 20-pin, 2 × 10, 0.1-inch socket. This plugs into a corresponding 2 × 10 pin header on the carrier board.