I have selected LPC1342 which is having ARM Cortex-M3 as core. Since this IC comes in SMD package only it can’t be soldered directly on perfo-board. Hence I had already designed a IC pad for 48-pin LPC1342. In previous post I’d used this same pad with SN65 line driver IC, so this pad design became an added advantage for me. This is how it looks-
Note :- SMD soldering requires good practice with soldering technique. I have used 25watt soldering iron but fine tip soldering iron is recommended. However it’s all a matter of soldering skill.
Now in order to solder this finished IC pad on perfo-board, I’ve used female header pins as shown in the above figure. Now our IC part is finished, our first step should be POWER. The first criterion of any design is power source. As of my case I’m using power from USB, so I need to solder USB first. So how to solder USB-B on a perfo-board. This is how to drill the perfo-board if the connector doesn’t matches hole size on board-
Now all connector size matches the hole size, this is soldering time. Put some flux on connector pins as-
After finishing USB soldering if you wish, measure the voltage at USB pins it should be 5V. But our LPC1342 ic works at 3.3V, so need to add a voltage regulator. Have a view at the schematic design (other link) for idea about USB power.
This is how it looks after finishing USB power connection. LM1117 (3.3V) is used as voltage regulator. Also connect a green LED between 3.3V and GND with a resistor (330ohm- 500ohm) in series. Now connect the USB power-
The glowing LED shows proper power connection. With header pins already soldered (along with header for SN65 for RS232 connection, which I’ll disscuss further) our board looks like this-
Now I need to solder RS232 port on board, this is some tricky work. I got an idea to solder RS232 port on board-
I’ve inserted RS232 in between the board edge, so that it can be easily soldered from one side of the board as shown in the above figure. For soldering other part of the connector, I’ve used normal solder wire. Finishing it looks like this-
Now I just needed to solder all the respecting pins of UART to SN65 to RS232.
One more crucial part to introduce in board is RESET & ISP buttons. Without these buttons IC can’t be put in programming mode I can’t start properly as well. Soldered RESET & ISP as per schematic design with proper resistor+capacitor combination. One red led should be connected to pin25 of IC to help debugging & to check initial programming.
Now you are ready to do the loop test of the board to assure proper basic functionality.
After getting assured with basic functionality, I need to add the features of a development board. For that I’ve introduced separate female header for PIO0, PIO1, PIO2, I2C, SPI, UART as per schematic.
The finished board after soldering all the connectors-
That’s all one can develop low cost development board of own as per chosen IC. Now it’s ready for firmware development.
When you connect device for the first time it will boot into USB MSC mode & will show CRP DIABLED directory. Use NXP ISP utility program to upload the blink program where pin25 is used as output pin.
To boot the device again in USB MSC mode for uploading any other program follow this video.