I am using the schematics and code from Gammon Software Solutions forum

"4-digit display made from minimal parts" at Gammon Forum : Electronics : Microprocessors : 4-digit display made from minimal parts

to drive my 4-segment common anode LED display. Since the original was developed for the

common cathode displays, I had to make changes in the following two parts:

Original:

```
// which bit to turn on to make a particular pin of the LED go high
const unsigned int DIG1 = 0x0200; // Q1 of second IC
const unsigned int DIG2 = 0x1000; // Q4 of second IC
const unsigned int DIG3 = 0x2000; // Q5 of second IC
const unsigned int DIG4 = 0x0002; // Q1 of first IC
```

Changed to:

```
const unsigned int DIG1 = ~0x0200; // Q1 of second IC
const unsigned int DIG2 = ~0x1000; // Q4 of second IC
const unsigned int DIG3 = ~0x2000; // Q5 of second IC
const unsigned int DIG4 = ~0x0002; // Q1 of first IC
```

and Original:

```
// which segments to light for each digit
const unsigned int digitPatterns [15] = {
SEGA | SEGB | SEGC | SEGD | SEGE | SEGF, // 0
SEGB | SEGC, // 1
SEGA | SEGB | SEGD | SEGE | SEGG, // 2
SEGA | SEGB | SEGC | SEGD | SEGG, // 3
SEGB | SEGC | SEGF | SEGG, // 4
SEGA | SEGC | SEGD | SEGF | SEGG, // 5
SEGA | SEGC | SEGD | SEGE | SEGF | SEGG, // 6
SEGA | SEGB | SEGC, // 7
SEGA | SEGB | SEGC | SEGD | SEGE | SEGF | SEGG, // 8
SEGA | SEGB | SEGC | SEGD | SEGF | SEGG, // 9
0, // space
SEGG, // hyphen
SEGA | SEGB | SEGC| SEGE | SEGF | SEGG, // A
SEGA | SEGE | SEGF | SEGG, // F
SEGD | SEGE | SEGF, // L
};
```

Changed to:

```
const unsigned int digitPatterns [15] = {
SEGG | SEGDP,// 0
SEGA | SEGD | SEGE | SEGF | SEGG | SEGDP, // 1
SEGC | SEGF | SEGDP, // 2
SEGE | SEGF | SEGDP , // 3
SEGA | SEGD | SEGE | SEGDP, // 4
SEGB | SEGE | SEGDP, // 5
SEGB | SEGDP, // 6
SEGD | SEGE | SEGF | SEGG | SEGDP, // 7
SEGDP, // 8
SEGE | SEGDP, // 9
SEGA | SEGB | SEGC | SEGD | SEGE | SEGF | SEGG | SEGDP, // space
SEGA | SEGB | SEGC | SEGD | SEGE | SEGF | SEGDP, // hyphen
SEGD | SEGDP, // A
SEGB | SEGC | SEGDP, // F
SEGA | SEGB | SEGC | SEGDP, // L
};
```

As suggested, I've also connected each segment to a 74HC595 through a 390 ohm resistor.

After these modifications, everything works as it should, except the decimal dot in front

of the tenths of seconds does not light. After many unsuccessful experiments, I have to

ask for help in making the decimal dot to work. Any pointers would be appreciated.