Write RF Subsystem Demo Code

[ericmutton]

Overview

Transmit and Receive may be in the name of the transceiver, but there are several devices that need to be tested in this system.

RF Transceiver

• Can the transceiver receive data from an existing radio transceiver?
• Can the transceiver transmit data to an existing transceiver?
• Can the transceiver switch between transmit and receive to achieve two-way communication?

RF Amplifier

This system must be measured given the VDD=3.3V. Maximum power input being +20 dBm means the +16 dBm maximum output power of the transceiver's internal PA can be set.

• Can the amplifier go from the +16 dBm input to +37 dBm? If not, what is achieved at 3.3 V? Given the +16 dBm input of the transceiver from its internal PA, if the RF amplifier achieves measurable gain to approximately +34 dBm at VDD=3.3V this is a very good result.
• If VDD=5.0V, the mounted control signal resistors may be adjusted for this new logic level. Can the logic stay at 3.3V?
  The RF is measurable using an RSSI meter of an off-the-shelf transceiver if no RF attenuators are available for test equipment.

What will happen when the amplifier is turned off? Per its description, no receive (unidirectional signal) should be seen. Can anything be measured when shutdown?

RF Switches

• Can the RF subsystem receive a signal through one of the two receive ports of the 4-to-1 switch? If so, can the correct band be selected?
• For transmission, can the RF switch being driven by a VNA move the input signal from either Port 2, 3, 4, or 5 to Port 1 (antenna)? If so, can the input signal be measured through the antenna port, Port 1?
• Before introducing the Amplifier Modulino in line with the RF transceiver, first attempt to use the transceiver directly. If the switch behavior is consistent, only then re-run the tests with amplification.

Outcomes

By implementing a small demonstration of two way communication using the RF subsystem, the following functionality can be verified against project requirements.

To verify if the RF Modulino can communicate over baseband (SPI) to the MCU Modulino:

• Can the transceiver complete a SPI transaction requesting for device information?
• Can the transceiver be asked to go to sleep and then be woken up?