PIC16LF1824T39A_12 Datasheet, PDF (320/418 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with XLP Technology

PIC16LF1824T39A
TABLE 28-1: RF TRANSMITTER PIN DESCRIPTION
Name
VDDRF
CTRL
RFOUT
VSSRF
DATA
XTAL
Function
VDDRF
CTRL
RFOUT
VSSRF
DATA
XTAL
Input Type
Power
CMOS
—
Power
CMOS
XTAL
Output Type
—
—
RF
—
CMOS
—
Description
RF Power Supply
Configuration Selection and Configuration Clock
Transmitter RF output
RF Power Supply
Configuration Data and Transmit Data
Crystal Oscillator
Note: The RF transmitter pins are independent
from the microcontroller pins.
FIGURE 28-2:
MODE SELECTION
TIMING DIAGRAM
t_START
The RF transmitter contains of a sigma-delta
fractional-N Phase-Locked Loop (PLL) frequency
synthesizer. Frequency Shift Keying (FSK) modulation
is made inside the PLL bandwidth. On-Off Keying
(OOK) modulation is made by turning on and off the
Power Amplifier (PA).
The reference frequency is generated by an internal
crystal oscillator. An external quartz crystal resonator is
connected to the XTAL pin and Ground (VSSRF). The
choice of crystal frequency depends on the frequency
band of choice.
The RF transmitter can deliver 0 dBm or +10 dBm into
a 50Ω load via the RFOUT pin. An external matching
network is required for each power setting and
frequency band for the best efficiency to the antenna.
28.2 Configuring the RF Transmitter
The CTRL and DATA pins are used to configure the RF
transmitter for transmit frequency, output power, modu-
lation, FSK frequency deviation, and Sleep time. Once
configured, the DATA pin is used to encode transmit
data.
28.2.1 POWER-ON RESET (POR)
At power-on, the CTRL pin is sampled as shown in
Figure 28-2 and depending on the CTRL pin logic level,
the RF transmitter will enter one of two Power-on Reset
(POR) values as shown in Table 28-3 and Table 28-4.
To continue using the RF transmitter with these POR
values, maintain the CTRL pin stable and at the pow-
ered-on logic level. With the DATA pin at logic ‘0’, the
RF transmitter will enter Sleep mode.
V_DDRF
CTRL
CTRL pin Sampled
If the POR settings are satisfactory for the application,
a microcontroller output pin can be freed by placing a
weak pull-up or pull-down resistor on the CTRL pin.
Only the DATA pin needs to be connected to an I/O pin.
28.2.2 RF TRANSMITTER REGISTERS
RF transmitter has three registers: Application,
Frequency, and Status. These are used to write and
read configuration parameters related to transmit
frequency, output power, modulation, FSK frequency
deviation, and Sleep time. A summary of register
values are shown in Table 28-2. A detailed explanation
of Application register is shown in Table 28-3,
Frequency register values in Table 28-4, and STATUS
register in Table 28-5.
To access the registers, the DATA line is sampled at
each low-to-high transition on the CTRL pin. A total of
24 transitions are required on the CTRL pin to success-
fully write or read a value in the registers. Register write
and read operations are shown in Figure 28-3.
Writing and reading the RF transmitter registers should
be done when the device is in Sleep mode. See
Section 28.2.4 “Sleep Mode”.
Note: It is recommended that a weak pull-up or
pull-down resistor be placed on the CTRL
pin to ensure the desired preset mode is
selected at power-on.
DS41657A-page 320
Preliminary
 2012 Microchip Technology Inc.