gz_led_driver waveform

This waveform shows the process of clocking in the four digits to be displayed. The digits are encoded as segments 'a' to 'g' mapped to bits 0 to 6, bit 7 ignored. As with all guzunty spi based cores, the bits are clocked in most significant bit (MSB) first. The digits are clocked in digit 0 through digit 3. At the bottom, you see the cached digit registers getting the values clocked into them.

There are four digit enable strobes and seven segment outputs. These are clocked too fast to see in the image above. The waveform below shows two refresh cycles at a time resolution that makes the strobing and segment enables visible.

Note that segments are illuminated when the segment bit is low. This suits a common anode seven segment display. For common cathode displays, the sense of the digit enables would be reversed and segments would be illuminated when the segment bit is high.