@ Nick Gammon
The debug output from the I2C_OSCDecimalFreqSetter.ino sketch is:
18.0490
42
88
The first is the frequency to set and the next two are the high (first) and low (second) bytes sent to the module. The frequency is set in the program, and the two bytes are calculated from that frequency. The scope measures a frequency of 18.0053 KHz. Once the program is the UNO, you can press the reset button any time and you won't get an error output from the program.
The module gets its power from the UNO board. The filtering shown on the schematic exists on the module's PCB. I think the problem is more with I2C than hardware. I have problems changing the frequency, but once set the frequency is stable and accurate.
@pylon:
I bought the board already assembled. The schematic shows switches but they are, in fact, soldered:
- OE Enabled.
- Pull-up resistors as on the schematic.
- ADR=GND => I2C address is 0x2E.
- Green power-on LED enabled.