PIC16F1847-I/SO Microchip Technology, PIC16F1847-I/SO Datasheet - Page 299

• Manufacturer Part Number: PIC16F1847-I/SO
• Description: 14 KB Flash, 1K Bytes RAM, 32 MHz Int. Osc, 16 I/0, Enhanced Mid Range Core 18 S
• Manufacturer: Microchip Technology

Specifications of PIC16F1847-I/SO

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

26.3
The Baud Rate Generator (BRG) is an 8-bit or 16-bit
timer that is dedicated to the support of both the
asynchronous and synchronous EUSART operation.
By default, the BRG operates in 8-bit mode. Setting the
BRG16 bit of the BAUDCON register selects 16-bit
mode.
The SPBRGH, SPBRGL register pair determines the
period of the free running baud rate timer. In
Asynchronous mode the multiplier of the baud rate
period is determined by both the BRGH bit of the TXSTA
register and the BRG16 bit of the BAUDCON register. In
Synchronous mode, the BRGH bit is ignored.
Table 26-3
baud rate.
for determining the baud rate and baud rate error.
Typical baud rates and error values for various
asynchronous modes have been computed for your
convenience and are shown in
advantageous to use the high baud rate (BRGH = 1),
or the 16-bit BRG (BRG16 = 1) to reduce the baud rate
error. The 16-bit BRG mode is used to achieve slow
baud rates for fast oscillator frequencies.
Writing a new value to the SPBRGH, SPBRGL register
pair causes the BRG timer to be reset (or cleared). This
ensures that the BRG does not wait for a timer overflow
before outputting the new baud rate.
If the system clock is changed during an active receive
operation, a receive error or data loss may result. To
avoid this problem, check the status of the RCIDL bit to
make sure that the receive operation is Idle before
changing the system clock.
 2011 Microchip Technology Inc.
EUSART Baud Rate Generator
(BRG)
Example 26-1
contains the formulas for determining the
provides a sample calculation
Table
26-3. It may be
Preliminary
EXAMPLE 26-1:
Calculated Baud Rate
For a device with F
of 9600, Asynchronous mode, 8-bit BRG:
Solving for SPBRGH:SPBRGL:
Desired Baud Rate
Error
PIC16(L)F1847
X
OSC
=
=
=
=
=
=
=
=
CALCULATING BAUD
RATE ERROR
Calc. Baud Rate Desired Baud Rate
------------------------------------------------------------------------------------------- -
----------------------------------------------------------------------- -
64 [SPBRGH:SPBRGL]
--------------------------------------------- 1

9615

----------------------------------
-------------------------------------------- -
Desired Baud Rate
16000000
----------------------- -
----------------------- - 1
-------------------------- -
64 25
16000000
25.042
9615 9600
of 16 MHz, desired baud rate

9600

64
9600
F
–
+

O S C
64
Desired Baud Rate
1
=

–
F
25
OS C

DS41453A-page 301
=
–
0.16%
–
+
1
