HW-0.23-mini
Blank Boards
These are the blank board's. Note: This documentation was written using 0.23r0 prerelease PCB's. Your PCBs look my slightly vary.
Soldering BGA components with Hot Air
If you bought the naked boards, you have to solder some parts using Hot Air. There are three Components which have BGA package (Ball grid array, e.g. you have no legs to solder with a solder iron, instead the connectors are underneath the components).
- Skytraq Venus 638FLPx GPS
- MPU-6000
- HMC5883L
Depending on your MS5607B version, you have to solder that part with hot air too (newer metal packages).
You have to solder twice because there are BGA parts on each side. Start with the smaller parts (MPU-6000 and HMC5883L), because they don't fall to ground when you solder the GPS on the other side.
First you have to dispense solder paste on the pads of the mentioned parts on your PCB. Use non-RoHS solder paste. This is a crucial task, don't use too much solder paste, and make sure it's evenly distributed.
Because we have big mass areas inside the board its not easy to heat up the paste fast enough. We recommend to heat up your board from beneath with a big hot air gun (set to about 150°C). This way your PCB is preheated to about 80°C on the other side. Then you can solder your part easily with a SMD rework hot air from the top. Set this temperature to about 270-300°C. If the solder paste doesn't melt at all or not on every side after 10 seconds, stop your process and start over again.
Test your GPS
We made the experience that the GPS is the most difficult part to solder. On different boards we had problems that some connectors didn't connected right. Therefor we recommend you to test the GPS separately before you proceed. The GPS is connected on the UART1 port (X6).
To do so, you have to assemble some more parts:
- X6
- R17/R19
- JP3 set to 3.3V (this way you will be able to "reverse power" your GPS through the connector)
- D5
- R31
- R65 (RESET)
- R66 (BOOTSEL)
- R64
- R70 and LED5 (too see something...)
- D2 and R68 (VBAT must be high)
TODO: Are this part numbers still correct for 0.23r1?
Afterwards you can connect a NG-USB on the UART1. Set your NG-USB to 3.3V. The NG-USB provides enough current to boot up the GPS. The RED LED should light up.
Now you can try to connect to your GPS using a terminal emulator at 9600 baud. You should see GPS NMEA messages.
Possible problems and solutions:
- If you see GPS NMEA messages at 4800 baud, the BOOT Enable PIN is not pulled down to ground. Make sure this resistor is on the board and your GPS is correctly soldered.
- If your LED lights up very short, your VBAT Pin might not be powered. Make your VBAT pin is connected to 3.3V through D2 and R68 and your GPS is correctly soldered.
Solder the rest
The rest can be soldered conventionally. Start with the multi-pin parts from the center. Solder the big parts and the one on the connectors at the edges at last.
Tips:
- When soldering capacitors, they are often connected to ground. Ground is difficult to heat up. Use a multimeter to check which side connects to ground, then start with the other side. Once one side is soldered, its easier to solder the other side.
The MS5607B is missing on this board.
High resultion pictures are available here:
