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The sampling rate of the APR2060Tx can be adjusted using an external POT (potentiometer) on Rosc pin (pin 3). Please refer to the application circuit example in the datasheet. The application circuit shows the Pin 3 is connected to a 47K value resistor.
If your circuit needs a fixed resistance value to match the sampling rate of the audio, a fixed value resistor can be used in place of POT on P3. Optionally, the POT gives the flexibility of changing the sampling rate. Use the POT with resistance value of 150K or 200k in series with the fixed value resistor will get the full range listed in the table below.
If you are using the APR2060DB demoboard, the maximum POT value is 100K.
For example, if your circuit has a fixed value of 47k resistor, by adjusting the POT to a resistance value of 150K, you will get more range on the resistance value. The total value would be 150K+47K = 197K (maximum resistance).
Here is the table with sample rate and corresponding duration and POT resistance, assuming your circuit has the P3 connected to a 47k resistor and in series with the POT. This table is for single message mode. For other modes (2/4 messages), the duration would be split for each message.
| Sampling Rate (khz) | Duration (sec) | POT Resistance (sec) |
Mode 1 msg (sec) | Mode 2 msg (sec) | Mode 4 msg (sec) |
|---|---|---|---|---|---|
| 12 | 42 | 47K | 42 | 21 | 10 |
| 11 | 46 | 63K | 46 | 23 | 12 |
| 10 | 51 | 79K | 51 | 26 | 13 |
| 9 | 56 | 100K | 56 | 28 | 14 |
| 8 | 64 | 120K | 64 | 32 | 16 |
| 7 | 73 | 143K | 73 | 36 | 18 |
| 6 | 85 | 173K | 85 | 43 | 21 |
To test your sample rate, always start with standard sampling rate of 12khz. Set the POT at 47K (without any additional resistance in series). Set the mode selection pins for single message mode. The record and play duration would be around 42 seconds.
For the same setting of POT and sampling rate, under 2 message mode, the duration would be around 11 seconds for each message.