Test Driven Development for Embedded C

Flash Driver

When I talk to embedded developers about applying TDD to embedded systems, the statement often comes up, “Yeah, but you can’t test-drive a device driver!” To that I reply, “Yes, you can.” This example will kill two birds with one stone. We’ll get right next to the silicon and develop part of a flash memory driver, and we’ll use a mock object to model and confirm the complex interactions between the driver and the hardware.

For the example, we’ll use the ST Microelectronics 16 Mb flash memory device (M28W160ECT). I chose this one for a number of reasons. The flash memory device requires a specific protocol, involving numerous device reads and device writes. There are also several failure modes, some of which would be very difficult ...