PIC16F872-E/SS Microchip Technology, PIC16F872-E/SS Datasheet - Page 257

• Manufacturer Part Number: PIC16F872-E/SS
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,SSOP,28PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F872-E/SS

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 64 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-SSOP
• Package: 28SSOP
• Device Core: PIC
• Family Name: PIC16
• Maximum Speed: 20 MHz
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 22
• Interface Type: I2C/SPI
• On-chip Adc: 5-chx10-bit
• Number Of Timers: 3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1997 Microchip Technology Inc.
The SSP consists of a transmit/receive Shift Register (SSPSR) and a Buffer register (SSPBUF).
The SSPSR shifts the data in and out of the device, MSB first. The SSPBUF holds the data that
was previously written to the SSPSR, until the received data is ready. Once the 8-bits of data
have been received, that information is moved to the SSPBUF register. Then the buffer full detect
bit, BF (SSPSTAT <0>), and interrupt flag bit, SSPIF, are set. This double buffering of the received
data (SSPBUF) allows the next byte to start reception before reading the data that was received.
Any write to the SSPBUF register during transmission/reception of data will be ignored, and the
write collision detect bit, WCOL (SSPCON<7>), will be set. User software must clear the WCOL
bit so that it can be determined if the following write(s) to the SSPBUF register completed suc-
cessfully. When the application software is expecting to receive valid data, the SSPBUF should
be read before the next byte of data to transfer is written to the SSPBUF. Buffer full bit, BF (SSP-
STAT<0>), indicates when SSPBUF has been loaded with the received data (transmission is
complete). When the SSPBUF is read, the BF bit is cleared. This data may be irrelevant if the SPI
is only a transmitter. Generally the SSP Interrupt is used to determine when the transmis-
sion/reception has completed. The SSPBUF can then be read (if data is meaningful) and/or the
SSPBUF (SSPSR) can be written. If the interrupt method is not going to be used, then software
polling can be done to ensure that a write collision does not occur.
ing of the SSPBUF (SSPSR) for data transmission. The shaded instruction is only required if the
received data is meaningful (some SPI applications are transmit only).
Example 16-1: Loading the SSPBUF (SSPSR) Register
The SSPSR is not directly readable or writable, and can only be accessed from addressing the
SSPBUF register. Additionally, the SSP status register (SSPSTAT) indicates the various status
conditions.
LOOP BTFSS SSPSTAT, BF
BCF
BSF
GOTO
BCF
MOVF
MOVWF RXDATA
MOVF
MOVWF SSPBUF
STATUS, RP1
STATUS, RP0
LOOP
STATUS, RP0
SSPBUF, W
TXDATA, W
;Specify Bank1
;
;Has data been received (transmit complete)?
;No
;Specify Bank0
;W reg = contents of SSPBUF
;Save in user RAM, if data is meaningful
;W reg = contents of TXDATA
;New data to xmit
Section 16. BSSP
Example 16-1
DS31016A-page 16-7
shows the load-
16