The HCM5883L came in two pieces that needed to be soldered together, shown on the left. While I have soldered in the past, my old yellow 25 year old soldering bolt broke a couple of years ago, and I bought a cheap kit including a bolt also some years ago. I almost never use it, since it is a pain to work with: it takes a long time to heat up and doesn’t seem to get warm enough. After struggling for maybe half an hour, I thought I had managed to solder every pin correctly.
I was wrong. When starting to program and read values using the library described at I2C Python Library – 3-Axis Digital Compass (HMC5883L) with the Raspberry Pi, I noticed that I got errors like ‘NoneType is not a float’ and at other times, only a value for the x axis but y and z both zero. ‘My board is broken!!’ No. My soldering job sucked.
After some Googling I found soldering is easy comic. Main take-outs were:
- Clean the tip with a wet sponge before each soldering action. This was new for me. I’ve used sandpaper in the past to clean the soldering tip, but did not do that before each action.
- Heat the pad and the lead (pin) for 1 second. Previously I had no clue about how long it would take to heat to an appropriate temperature.
- Then add the soldering – until it becomes a fluid.
- Then stop feeding solder and hold for 1 more second. This is the hard part. I used to immediately remove both solder and bolt once the solder became fluid, but by keeping the bolt one more second, the tin would surround the lead.
After some careful internetting, I chose the Toolcraft ST-50D soldering station, available for €89,99.
After ordering, it became clear that it was to be delivered from Germany and would take a couple of days.
I could not wait a couple of days to try out some of the techniques I had read about, so I thought lets try to fix the bad connections. Heat the bolt. In the meantime prepare a wet sponge for inter-action cleaning. I applied the soldering-is-easy method, and the first lead was done in 5 seconds. Surprize surprize, that was quick! Clean the tip, on to next lead. Again. I think I was finished within a minute, and all the leads looked like a really good connection.
This is the final result. All connections work without problems.
Next onto programming and test if it is useful enough to use on the telescope.