ZX Interface Z - The Hardware, part 3
Let's interact Welcome to the third part of the ZX Interface Z hardware overview. On the first part we looked with some detail at the expansion connector and the power supplies, the second part focused on the voltage level converters and the back connector. In this blog post we will look at the user interface and the SD card. The buttons The Interface Z has 3 buttons that can be used to control the Interface. One of the buttons is tied to an hard reset, which will reset the ESP32, causing the FPGA to be reprogrammed and the ZX Spectrum to also reset accordingly. Two other buttons exist, which are software controlled, but one of them has also an hidden purpose. Some of these buttons (S1 and S2) include an hardware low-pass filter, comprised by the pull-up resistor and the capacitor to the ground. This helps to avoid excessive bouncing when the switch is pressed or released. The S3 switch does not include a low-pass filter, and delegates the debouncing to software. All three bu...