the PW1-928’s RF section is completely shut down and
the processor enters an idle state. In standby state, the
receiver is always inactive. However, a transmit burst can
be initiated in standby state by driving a specifically
formatted data stream on the PW1-928’s SI pin.
If the PW1-928 is in standby (STBY pin floating/high)
and activity is detected on the PW1-928’s SI serial input
pin, the PW1-928 will temporarily come out of low power
mode, transmit a single burst, and then revert back to
standby. The format for a “standby transmit” is specific
and consists of a 1 mS low-going pulse applied to the
PW1-928 serial input followed by a 2 mS delay. Following
the 2 mS delay, the data packet can be transferred and
By default, the PW1-928’s UART packet format
is fixed at one start bit, eight data bits, no parity,
and one stop bit. The PW1-928’s default baud rate
is 9600 bps. Higher baud rates of 38. 4 kbps and
57. 6 kbps are also supported. In command/
programming mode, the PW1-928 requires an RS-
232 serial port baud rate of 2400 bps.
The PW1-928’s embedded protocol
automatically transmits the data that is driven on the SI
pin. All encoding, transmitting, receiving, and decoding
functions are handled by the PW1-928’s internal
processor. This automatic transmission capability allows
the PW1-928 to stream data continuously at 9600 bps
with no buffer overflows. The PW1-928 supports point-to-point communication links and broadcast topologies.
While in receive mode, the PW1-928’s PIC constantly
monitors the SX1272 looking for a valid packet receive
flag. When the PW1-928’s PIC detects a receive flag, the
PIC downloads all the data for the packet into a buffer,
checks for valid framing, address, and checksum and —
assuming a success on all those tests — transfers the
payload to a 64-byte FIFO.
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56 April 2017
■ PHOTO 3. The PW1-928 dev kit provides a regulated 3. 3 volt
power rail and allows the user to access all of the PW1-928’s RF
and digital hardware facilities.
■ SCHEMATIC 1. The PW1-928 dev kit provides clean
regulated power, access to the PW1-928’s indication
signals, and a CMOS compatible serial interface.
PW1-928 RF Data
CCS C Compiler