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FM-100 Page 10
MICROCONTOLLER DESCRIPTION
The coding of the microcontroller is set up for a simple process of changing
frequency. As you will see, there is more than meets the eye, but it’s not so
complex when you give it a look.
We will start with two given conditions: 1) The unit is powered up, and 2) The
unit has been set in setup mode. In this state the tens decimal point is blinking
and your frequency may be changed.
1. User presses FREQ UP button.
2. Microcontroller stops scanning the LD (Lock Detect) line, sees what key the
user has pressed.
3. It’s a Frequency key, is the unit in setup mode?
4. Yes, increase the frequency value in RAM by 200KHz.
5. Send the appropriate divide by N to the PLL (U2) along with the rest of the
required data.
6. Decode the display digits, then send the correct bits to the display.
7. Mute the microphone.
8. Send confirm beep.
9. Un-mute the microphone.
10. Wait for key release, if no key release after some time, repeat from step 4.
11. Continue polling LD and updating status indicators.
We hope all of this information helps you understand better what is going on in
the FM-100, and will lead to some insight when you are having assembly
troubles or something isn’t working properly. Remember most projects like this
are made up of many smaller ones, all you have to do is break them down to
understand them better. Now on to building!!!
Содержание FM-100
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