The circuit forms an interface between a micro controller and a 8 by 8 Dual Colour Common Anode LED Module. This type of module has two LEDs per pixel, each row has 8 pixels, with 8 rows. The anodes of each LED in a row are connected, with 16 columns formed by connecting together the cathode of an LED from each row.
A high side switch is needed to turn on/off a row and must be able to source approximately 240 milliamperes (16 multiplied by 15 milliamperes). A low side switch is needed to turn on/off a column, but only one LED is on per column so it only needs to sink 15 milliamperes.
For the high side switching I used a TD62783APG 8 Channel High-Voltage Source Driver from Toshiba Semiconductor. It’s very important that only one output from the TD62783 is on at any one time so I used a 74HC238 3-to-8 Decoder from NXP to control the row selection. For the low side switching we used two 74HC595 8-bit Shift Registers from NXP.
For more detail: LED Matrix Display using TD62783 microcontroller
This free embedded project also found using:
- circuit matrix led
- common anode matrix with td 62783
- td 62783 source driver with led matrix