Small sketch for the Arduino to display characters on an HDSP2010. Somewhat hacked-up for a demo at Dorkbot Bristol on 2026-07-14.
Any of the displays in the HDSP2000 series should work (they're different colours). This is a 5x7 matrix LED display originally made by Hewlett Packard.
It appears as a 28-bit shift register (4 digits of 7 rows each) and 5 column driver inputs. The columns are driven by five PNP transistors configured as high-side drivers and connected to Arduino pins 4, 5, 6, 7, and 8. The shift register input is connected to Arduino pin 2 and the clock to Arduino pin 3
| Name | Arduino Pin | HDSP2010 Pin |
|---|---|---|
| DATA | 2 | 12 |
| CLK | 3 | 10 |
| COL1 | 4 | 1 |
| COL2 | 5 | 2 |
| COL3 | 6 | 3 |
| COL4 | 7 | 4 |
| COL5 | 8 | 5 |
| GND | Gnd | 11 |
| VCC | +5V | 8, 9 |
