PIC24FJ128GB MICROCHIP [Microchip Technology], PIC24FJ128GB Datasheet - Page 190

• Manufacturer Part Number: PIC24FJ128GB
• Description: 64/80/100-Pin, 16-Bit Flash Microcontrollers with USB On-The-Go (OTG)
• Manufacturer: MICROCHIP [Microchip Technology]

PIC24FJ256GB110 FAMILY
16.1
The UART module includes a dedicated 16-bit Baud
Rate Generator. The UxBRG register controls the
period of a free-running, 16-bit timer. Equation 16-1
shows the formula for computation of the baud rate
with BRGH = 0.
EQUATION 16-1:
Example 16-1 shows the calculation of the baud rate
error for the following conditions:
• F
• Desired Baud Rate = 9600
EXAMPLE 16-1:
DS39897B-page 188
Note 1:
Desired Baud Rate
Solving for UxBRG value:
Calculated Baud Rate= 4000000/(16 (25 + 1))
Error
Note 1:
CY
= 4 MHz
2:
UART Baud Rate Generator (BRG)
UxBRG
UxBRG
UxBRG
Baud Rate =
UxBRG =
F
frequency (F
Based on F
and PLL are disabled.
Based on F
CY
denotes the instruction cycle clock
UART BAUD RATE WITH
BRGH = 0
BAUD RATE ERROR CALCULATION (BRGH = 0)
= F
= ((F
= ((4000000/9600)/16) – 1
= 25
= 9615
= (Calculated Baud Rate – Desired Baud Rate)
= (9615 – 9600)/9600
= 0.16%
16 • (UxBRG + 1)
CY
16 • Baud Rate
OSC
CY
Desired Baud Rate
CY
= F
CY
= F
/2).
/(16 (UxBRG + 1))
F
F
CY
OSC
/Desired Baud Rate)/16) – 1
CY
OSC
(1,2)
/2, Doze mode
/2, Doze mode and PLL are disabled.
– 1
Preliminary
The maximum baud rate (BRGH = 0) possible is
F
possible is F
Equation 16-2 shows the formula for computation of
the baud rate with BRGH = 1.
EQUATION 16-2:
The maximum baud rate (BRGH = 1) possible is F
(for UxBRG = 0) and the minimum baud rate possible
is F
Writing a new value to the UxBRG register causes the
BRG timer to be reset (cleared). This ensures the BRG
does not wait for a timer overflow before generating the
new baud rate.
CY
Note 1:
CY
/16 (for UxBRG = 0) and the minimum baud rate
/(4 * 65536).
2:
Baud Rate =
UxBRG =
CY
F
frequency.
Based on F
and PLL are disabled.
CY
/(16 * 65536).
(1)
denotes the instruction cycle clock
UART BAUD RATE WITH
BRGH = 1
© 2008 Microchip Technology Inc.
4 • (UxBRG + 1)
CY
4 • Baud Rate
= F
F
F
OSC
CY
CY
(1,2)
/2, Doze mode
– 1
CY
/4