I pulled out the weather radio project today to see what I could get done in a few hours. I was pretty close on finishing off the hardware but I fell a little short right at the end. I found I had forgotten to buy something to convert the regulated 5V to 3.3V for the radio (and PIC since they’re tied together on I2C). I ran into a few issues I totally spaced:1. The Si4707 requires a reset after power up .. it ignores I2C if you don’t.
2. Pull-ups.. duh, not only on I2C which I had, but don’t forget the Si4707 reset (oops).
I ended up buying a couple random Digikey parts at the ham radio convention and guess what? 10@ MCP1802T-3002I/OT (300mA 3.0V LDO) ..they are SOT23-5 and I had JUST gotten 10 break-out boards in the mail so I ended up having a 5V3.3V converter (close enough anyways, as the PIC and Si4707 work down to 2.7V).. soldered it up but I didn’t have time to pop it in. I used the Weller but I think I’m going to solder another one with the new hot air gun I got this week. I ordered one of those cheap 858D rework stations; I don’t plan on using it too much so hopefully it’ll do the trick. I also got a bunch of SMD protoboards.. so I get to practice reflow this week.
Tomorrow I should be able to finish up the radio and then it’s all software.
The photo isn’t the most exciting workbench shot but you can see that 858D in the back corner. The WX radio is the black box right up close to the left.