I am working on an updated design to the DG5. Rather than being a shield for an Arduino, this PCB has the Atmel 328P chip on the board, along with room for a proper crystal, reset switch, and FTDI programming header. The main reason for doing this is the preferred Arduino to use – the Duemilanove – is getting pretty hard to find as this was a 2009 model. The later boards all use a ceramic resonator as the clock for the chip – which isn’t nearly accurate or stable enough in the role of a frequency counter.
The input side of the board is unchanged, the Arduino Shield headers have been removed and some rearranging of IC4 & IC5 to better allow the addition of the Atmel 328P (what is used on the Arduino’s) and the supporting hardware.
There is no USB port on this board. It would best to still have an Arduino to be able to load the software, as the bootloader comes on the chip when you buy an Arduino. If you have a chip programmer, you can do this without an Arduino. Once the chip has an Arduino bootloader, you can program via the FTDI header – a TTL interface that works with something like this from Adafruit:
More to come, I just sent off for a set of prototype boards. There is no advantage upgrade if you already have the shield working – this is to address the lack of crystal controlled Arduinos moving forward if all goes well. This also means you’ll need to have a programmer or arduino anyway – and need one of these FTDI boards (above) that cost as much as an Arduino anyway.
Steve – KV6O