If, with a little help from the circuit diagrams, board layouts and other documentation you have built the VFD module from the first installment of this series, you may have discovered that not a lot happens when you power it up. The reason behind this is that the microcontroller in the display module needs firmware, so that it can understand the control commands sent to it. This firmware and, last but not least, the code for the Raspberry Pi, forms the topic of this second and final installment.