PIC16F877A-I/PT Microchip Technology Inc., PIC16F877A-I/PT Datasheet - Page 109

• Manufacturer Part Number: PIC16F877A-I/PT
• Description: 44 PIN, 7 KB FLASH, 368 RAM, 33 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F877A-I/PT

• A/d Inputs: 8-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 33
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 44-pin TQFP
• Programmable Memory: 14K Bytes
• Ram Size: 368 Bytes
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

10.3.2
Once synchronous mode is selected, reception is
enabled
(RCSTA<5>), or enable bit CREN (RCSTA<4>). Data is
sampled on the RC7/RX/DT pin on the falling edge of
the clock. If enable bit SREN is set, then only a single
word is received. If enable bit CREN is set, the recep-
tion is continuous until CREN is cleared. If both bits are
set, CREN takes precedence. After clocking the last bit,
the received data in the Receive Shift Register (RSR)
is transferred to the RCREG register (if it is empty).
When the transfer is complete, interrupt flag bit RCIF
(PIR1<5>) is set. The actual interrupt can be enabled/
disabled
(PIE1<5>). Flag bit RCIF is a read only bit, which is
reset by the hardware. In this case, it is reset when the
RCREG register has been read and is empty. The
RCREG is a double buffered register (i.e., it is a two
deep FIFO). It is possible for two bytes of data to be
received and transferred to the RCREG FIFO and a
third byte to begin shifting into the RSR register. On the
clocking of the last bit of the third byte, if the RCREG
register is still full, then overrun error bit OERR
(RCSTA<1>) is set. The word in the RSR will be lost.
The RCREG register can be read twice to retrieve the
two bytes in the FIFO. Bit OERR has to be cleared in
software (by clearing bit CREN). If bit OERR is set,
transfers from the RSR to the RCREG are inhibited, so
it is essential to clear bit OERR if it is set. The ninth
TABLE 10-9:
0Bh, 8Bh,
10Bh,18Bh
0Ch
18h
1Ah
8Ch
98h
99h
Legend: x = unknown, - = unimplemented, read as '0'. Shaded cells are not used for synchronous master reception.
Note 1: Bits PSPIE and PSPIF are reserved on PIC16F873/876 devices; always maintain these bits clear.
Address
2001 Microchip Technology Inc.
by
by
USART SYNCHRONOUS MASTER
RECEPTION
INTCON
PIR1
RCSTA
RCREG
PIE1
TXSTA
SPBRG
Name
setting
setting/clearing
REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION
USART Receive Register
Baud Rate Generator Register
PSPIF
PSPIE
CSRC
SPEN
Bit 7
GIE
either
(1)
(1)
PEIE
ADIF
ADIE
Bit 6
enable
RX9
TX9
enable
SREN CREN
TXEN
RCIE
RCIF
Bit 5
T0IE
bit
bit
SREN
SYNC
INTE
TXIE
RCIE
Bit 4
TXIF
SSPIE CCP1IE TMR2IE TMR1IE
SSPIF
RBIE
Bit 3
—
—
receive bit is buffered the same way as the receive
data. Reading the RCREG register will load bit RX9D
with a new value, therefore, it is essential for the user
to read the RCSTA register before reading RCREG in
order not to lose the old RX9D information.
When setting up a Synchronous Master Reception:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. If any error occurred, clear the error by clearing
11. If using interrupts, ensure that GIE and PEIE
CCP1IF TMR2IF TMR1IF
BRGH
FERR
Bit 2
T0IF
Initialize the SPBRG register for the appropriate
baud rate (Section 10.1).
Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
Ensure bits CREN and SREN are clear.
If interrupts are desired, then set enable bit
RCIE.
If 9-bit reception is desired, then set bit RX9.
If a single reception is required, set bit SREN.
For continuous reception, set bit CREN.
Interrupt flag bit RCIF will be set when reception
is complete and an interrupt will be generated if
enable bit RCIE was set.
Read the RCSTA register to get the ninth bit (if
enabled) and determine if any error occurred
during reception.
Read the 8-bit received data by reading the
RCREG register.
bit CREN.
(bits 7 and 6) of the INTCON register are set.
OERR
TRMT
INTF
Bit 1
RX9D
TX9D
Bit 0
R0IF
PIC16F87X
0000 000x
0000 0000
0000 -00x
0000 0000
0000 0000
0000 -010
0000 0000
Value on:
POR,
BOR
DS30292C-page 107
Value on all
0000 000u
0000 0000
0000 -00x
0000 0000
0000 0000
0000 -010
0000 0000
RESETS
other