Background
The matrix consists of 6 rows and 24 columns of LEDs which are soldered to a PCB and connected to rows of header pins that control current to an individual LED. Through this system we are able to control the input of a single LED allowing patterns to be shifted across the matrix and have columns of LEDs appear on at the same time.
The matrix consists of 6 rows and 24 columns of LEDs which are soldered to a PCB and connected to rows of header pins that control current to an individual LED. Through this system we are able to control the input of a single LED allowing patterns to be shifted across the matrix and have columns of LEDs appear on at the same time.
Implementation
The matrix is connected to the transistor circuit and the shift registers. The transistor circuit is connected to the 6 header pins on the left side and provides power to all the LEDs in a row. The shift registers are connected to the 24 header pins along the bottom of the board and they control which bit pattern is being sent to which LED.
Test Procedure
In order to verify the matrix was working correctly we connected a wire to a 5V power supply and attached it to one of the 6 header pins to power a row. The transistor circuit was not used for this testing as only 1 LED would be on at a time. We then took a second wire attached to the same power supply and attached it to each of the 24 header pins one at a time. The result we were looking for was having a single LED in the row turn on.
Test Results
Our first tests of the board showed we had two solder bridges that caused rows 1 & 2 and 4 & 5 to light up at the same time. Using a high powered microscope we went over all of our solder points and scraped any excess solder that that ran off pads.
Second round of testing showed that the removed solder did not solve our problem so we investigated our header pins. We found solder bridges in the header pins and in the process of fixing them 3 pads lifted from the board. We ran jumpers from the pins to the traces and tested again.
Third round of testing showed that we still had solder bridges so we used the microscope again and found more excess solder. After clearing the solder we retested and found all of the solder bridges had been cleared and single LEDs were turning on.
The matrix is connected to the transistor circuit and the shift registers. The transistor circuit is connected to the 6 header pins on the left side and provides power to all the LEDs in a row. The shift registers are connected to the 24 header pins along the bottom of the board and they control which bit pattern is being sent to which LED.
Test Procedure
In order to verify the matrix was working correctly we connected a wire to a 5V power supply and attached it to one of the 6 header pins to power a row. The transistor circuit was not used for this testing as only 1 LED would be on at a time. We then took a second wire attached to the same power supply and attached it to each of the 24 header pins one at a time. The result we were looking for was having a single LED in the row turn on.
Test Results
Our first tests of the board showed we had two solder bridges that caused rows 1 & 2 and 4 & 5 to light up at the same time. Using a high powered microscope we went over all of our solder points and scraped any excess solder that that ran off pads.
Second round of testing showed that the removed solder did not solve our problem so we investigated our header pins. We found solder bridges in the header pins and in the process of fixing them 3 pads lifted from the board. We ran jumpers from the pins to the traces and tested again.
Third round of testing showed that we still had solder bridges so we used the microscope again and found more excess solder. After clearing the solder we retested and found all of the solder bridges had been cleared and single LEDs were turning on.