PIC16F636-I/P Microchip Technology Inc., PIC16F636-I/P Datasheet - Page 102

• Manufacturer Part Number: PIC16F636-I/P
• Description: 14 PIN, 3.5 KB FLASH, 128 RAM, 12 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F636-I/P

• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 12
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 14-pin PDIP
• Programmable Memory: 3.5K Bytes
• Ram Size: 128 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC12F635/PIC16F636/639
11.31.3.1
The AFE’s RSSI output is an analog current. It needs an
external analog-to-digital (ADC) data conversion device
for digitized output. The ADC data conversion can be
accomplished by using a stand-alone external ADC
device or by firmware utilizing MCU's internal
comparator along with a few external resistors and a
capacitor. For slope ADC implementations, the external
capacitor at the LFDATA pad needs to be discharged
before data sampling. For this purpose, the internal pull-
down MOSFET on the LFDATA pad can be utilized. The
MOSFET can be turned on or off with bit RSSIFET<8> of
the Configuration Register 2 (Register 11-3). When it is
turned on, the internal MOSFET provides a discharge
path for the external capacitor. This MOSFET option is
valid only if RSSI output is selected and not controllable
by users for demodulated or carrier clock output options.
See separate application notes for various external ADC
implementation methods for this device.
FIGURE 11-16:
DS41232B-page 100
ANALOG-TO-DIGITAL DATA
CONVERSION OF RSSI SIGNAL
LFDATA/RSSI/
SCLK/ALERT
CCLK/SDIO
POWER-UP SEQUENCE
CS
LFDATA
(output)
(open collector
ALERT
output)
Preliminary
11.32
11.32.1
The AFE SPI interface communication is used to read
or write the AFE’s Configuration registers and to send
command only messages. For the SPI interface, the
device has three pads; CS, SCLK/ALERT, and
LFDATA/RSSI/CCLK/SDIO. Figure 11-15, Figure 11-
14, Figure 11-16 and Figure 11-17 shows examples of
the SPI communication sequences.
When the device powers up, these pins will be high-
impedance inputs until firmware modifies them
appropriately. The AFE pins connected to the MCU
pins will be as follows.
CS
• Pin is permanently an input with an internal pull-up.
SCLK/ALERT
• Pin is an open collector output when CS is high.
LFDATA/RSSI/CCLK/SDIO
• Pin is a digital output (LFDATA) so long as CS is
An internal pull-up resistor exists internal to the
AFE to ensure no spurious SPI communication
between powering and the MCU configuring its
pins. This pin becomes the SPI clock input when
CS is low.
high. During SPI communication, the pin is the
SPI data input (SDI) unless performing a register
Read, where it will be the SPI data output (SDO).
AFE C
SPI COMMUNICATION
onfiguration
© 2005 Microchip Technology Inc.