The ESPboy Walkie-Talkie module uses SA868 transceiver allows you to use your ESPboy as an Walkie-Talkie radio. You can buy this module ready-made or make it yourself.
1.1 SA868 module
1.3 MAX9814 microphone (i used one with manual gain adjustment)
1.4 speaker 4Ohm 3w (i used speaker from the old notebook)
1.6 antenna
NOTES:
- take into account connectors to fit one to other (antenna connector on the board and antenna connector on the antenna itself)
- take into account the length of the antenna, the optimal length (for the best perfomance/range) should be 1xY; 1/2xY; 1/4xY; 1/8xY where Y = 300/Frequency (longer antenna - better signal).
example: Let it be working frequency 433mhz. Antenna length = (300/433)x(1/4) = 0,173m = 17,3sm
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SA868 1 (Audio ON) -> ESPboy B6, LTK5128board Mute
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SA868 3 (Audio output) -> LTK5128board Audio_Input
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SA868 5 (PTT) -> ESPboy B7
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SA868 6 (PD/PowerDown) -> ESPboy VCC
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SA868 7 (High/Low power) -> SA868 10 for LowPower or keep opened to HighPower (do NOT connect to VCC!)
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SA868 8 (VBAT) -> ESPboy VCC
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SA868 9 (GND) -> ESPboy GND
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SA868 10 (GND) -> ESPboy GND
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SA868 12 (ANT) -> antenna central wire (do not forget to solder ground antenna wire to GND)
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SA868 16 (RXD) -> ESPboy SS (GPIO15/D8)
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SA868 17 (TXD) -> ESPboy MI (GPIO12/D6)
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SA868 18 (MIC) -> MAX9814 OUT
NOTES:
- connect ESPboy VSS and ESPboy GND to MAX9814board (VCC and GND) and LTK5128board (Power +5v and ASND)
- connect antenna ground wire to ESPboy GND
- connect speaker to LTK5128 amplifier board "Audio output +" and "Audio output -"
- connect antenna itself
NOTE: Before compilation, set Arduino IDE settings
- Board: ESP8266 WeMos D1 mini
- CPU frequency: 160Mhz