147
/
246
ABOV Semiconductor
UART
Un.BFR
Baud rate Fraction Counter Register
9.3.9
Baud rate Fraction Counter Register is 8-bit register.
U0.BFR=0x4000_8024, U1.BFR=0x4000_8124
7
6
5
4
3
2
1
0
BFR
0x00
RW
7
0
BFR
Fractions counter value.
0
Fraction counter is disabled
N
Fraction counter enabled. Fraction compensation mode is
operating. Fraction counter is incremented by FCNT.
Table9.7. Example of baud rate calculation
UART
clock
=40 MHz
Baud rate
Divider
FCNT
Error (%)
1200
2083
85
0.00%
2400
1041
170
0.00%
4800
520
213
0.00%
9600
260
106
0.00%
19200
130
53
0.00%
38400
65
262
0.00%
57600
43
103
0.00%
115200
21
179
0.01%
FCNT = Float ∗ 256
FCNT value can calculated above equation. For example, the target baud rate is 4800 bps and UART
clock
is 40MHz case,
the BDR value is 520.8333. The integer number 520 should be the BDR value and the floating number 0.8333 will make
the FNCT value as below.
FCNT = 0.8333 * 256 = 213.3333, so the FCNT value is 213.
8-bit fractional counter will count up by FCNT value every (baud rate)/16 periods and whenever fractional counter
overflow is happen, the divisor value will increment by 1. So this period will be compensated. Then next period, the
divisor value will return to original set value.
Summary of Contents for AC30M1x64
Page 3: ...3 246 ABOV Semiconductor INTRODUCTION SECTION 1 INTRODUCTION...
Page 4: ...4 246 4 246 AC30M1x64 1x32 ABOV Semiconductor OVERVIEW CHAPTER 1...
Page 18: ...18 246 18 246 ABOV Semiconductor AC30M1x64 1x32 CPU CHAPTER 2...
Page 22: ...22 246 22 246 ABOV Semiconductor AC30M1x64 1x32 Boot Mode CHAPTER 3...
Page 26: ...26 246 26 246 ABOV Semiconductor AC30M1x64 1x32 SECTION 2 PERIPHERALS...
Page 27: ...27 246 ABOV Semiconductor System Control Unit SCU SYSTEM CONTROL UNIT SCU CHAPTER 1...
Page 69: ...69 246 ABOV Semiconductor Port Control Unit PCU PORT CONTROL UNIT PCU CHAPTER 2...
Page 85: ...85 246 ABOV Semiconductor General Purpose I O GPIO GENERAL PURPOSE I O GPIO CHAPTER 3...
Page 92: ...92 246 92 246 AC30M1x64 1x32 ABOV Semiconductor FLASH MEMORY CONTROLLER CHAPTER 4...
Page 105: ...105 246 ABOV Semiconductor Internal SRAM INTERNAL SRAM CHAPTER 5...
Page 107: ...107 246 ABOV Semiconductor Watch Dog Timer WATCH DOG TIMER WDT CHAPTER 6...
Page 113: ...113 246 ABOV Semiconductor 16 bit Timer 16 BIT TIMER CHAPTER 7...
Page 129: ...129 246 ABOV Semiconductor FRT FREE RUN TIMER FRT CHAPTER 8...
Page 134: ...134 246 134 246 ABOV Semiconductor AC30M1x64 1x32 FUNCTION DESCRIPTION 8 3...
Page 135: ...135 246 UART ABOV Semiconductor UNIVERSAL ASYNCHRONOUS CHAPTER 9 RECEIVER TRANSMITTER UART...
Page 151: ...151 246 ABOV Semiconductor UART Figure 9 6 Transmit interrupt timing diagram...
Page 152: ...152 246 152 246 ABOV Semiconductor AC30M1x64 1x32 SERIAL PERIPHERAL INTERFACE SPI CHAPTER 10...
Page 164: ...164 246 164 246 ABOV Semiconductor AC30M1x64 1x32 I2 C Interface CHAPTER 11...
Page 185: ...185 246 ABOV Semiconductor Motor PWM MOTOR PULSE WIDTH MODULATOR CHAPTER 12 MPWM...
Page 215: ...215 246 ABOV Semiconductor Divider DIVIDER DIV64 CHAPTER 13...
Page 221: ...221 246 ABOV Semiconductor 12 BIT A D Converter 12BIT A D CONVERTER CHAPTER 14...
Page 235: ...235 246 ABOV Semiconductor CHARACTERISTIC SECTION 3 CHARACTERISTIC...
Page 236: ...236 246 236 246 ABOV Semiconductor AC30M1x64 1x32 Electrical Characteristic CHAPTER 1...
Page 243: ...243 246 ABOV Semiconductor Package Package CHAPTER 2...