Controlling RF Transmitter Power via Microcontroller and SPI for Battery Operation

The discussion addresses controlling power to an RF transmitter connected via SPI to a microcontroller in a battery-powered home automation system. The main challenge is to power the microcontroller and RF chip only when transmitting commands triggered by capacitive touch switches, to conserve battery life. Suggested solutions include using a MOSFET as a low-side or high-side switch controlled by a microcontroller I/O pin to power the RF transmitter on demand. Alternatively, if the RF chip supports an enable or power-down (PDN) pin, it can be toggled to reduce power consumption without fully cutting power. Another approach is leveraging the microcontroller’s low-power sleep modes to keep it mostly off, waking periodically to poll the capacitive touch switch, thus minimizing current draw. The specific components discussed are the Microchip MRF24J40MB RF transceiver and the Atmel ATmega16 microcontroller. Considerations include ensuring the MOSFET can handle the transmitter’s current and matching power requirements if powering the transmitter directly from a microcontroller pin. Battery selection and efficient power management are critical due to the limited battery life when continuously powered.
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