With all good designs, the attention to detail is what makes a system an excellent design. One feature of the ProtoDev DX is the ability to use one of two completely different package types on the same development PCB.
Development boards generally allow a user to insert a device tye based on the package type ie 28 PIN dip or 40 PIN dip. When compared, the 28 PIN DIP is slim and the fun comes to an end when you reach 28 PINS. The 40 PIN device is much wider, ofers more PINs and generally more features.
When developing, you may start with the 40 PIN device and then realise you can reduce the cost of your design’s manufacture by optimising your project to run on a 28 PIN device. Going the other way, adding new features often means more I/O and if your 28 PINs are all used up a 40 PIN device will be required.
This discussion revolves around selecting a development PCB that will serve the needs of the development cycle no matter what the choice in device size, package features, etc.
Seen in the image below, the ProtoDev DX is capable of housing 1 of 2 devices. This means that as above, you would only need one PCB and the PCB will be usuable for your project as the project grows from a 28 PIN device or is optimised from a 40 PIN device to a 28 PIN device.
Although not a big secret, it was interesting to note that the PIC28s IO could be overlayed by the 40 PIN pics I/O. This is part of the Microchip compatibility strategy which enables code to be migrated from one device to the next with minimal changes. The Protodev DX leverages this strategy by enabling the user to select a device in either the 28 or 40 PIN packages and be able to replace the device with a different PIC be it packages or family. *
Why usefull: well rather than having to own a 28 and 40 pin development board, only 1 would be required. It’s a cost saving and makes development easier and more productive.
* This observation applies more specifically to PICs in the same family and can apply to devices from different families. Consult the respective device’s datasheet for more information. I/O location can change between devices along with the features available.