ML610Q412P-NNNTB03A7 Rohm Semiconductor, ML610Q412P-NNNTB03A7 Datasheet - Page 150

• Manufacturer Part Number: ML610Q412P-NNNTB03A7
• Description: MCU 8BIT 16K FLASH 120-TQFP
• Manufacturer: Rohm Semiconductor

Specifications of ML610Q412P-NNNTB03A7

• Core Processor: nX-U8/100
• Core Size: 8-Bit
• Speed: 625kHz
• Connectivity: I²C, SSP, UART/USART
• Peripherals: LCD, POR, PWM, WDT
• Number Of I /o: 14
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 1.1 V ~ 3.6 V
• Data Converters: A/D 2x12b, 2x24b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

However, actual 500kHz RC oscillation clock has temperature variation and production tolerance, the calculation by
using the fixed value of 500kHz can not make accurate baud-rate. To compensate it, count the frequency in the
frequency measurement mode to set the baud-rate again before operating UART communication.
After finishing the clock count in the frequency measurement mode, assuming HTBCLK is 451kHz, data of TM2C
register and TM3C register will be:
10.3.3
For example, when the target baud-rate is 9600bps and the clock is HSCLK(500kHz), the UART0 baud-rate register
(UA0BRTH, UA0BRTL) should be set as follows. See Section 14.3.2. in UART chapter.
Baud-rate[bps]
300
600
1200
2400
4800
9600
19200
38400
57600
UA0BRTH, UA0BRTL = 500000/9600 - 1 = 51 (decimal) = 33(Hexadecimal)
As (437 / 32768) sec is equivalent to 128 clocks at 9600Hz (more precisely, 9598Hz), a division of the count
(N1) by 128 equals frequency ratio (N2) between the frequency of HTBCLK and 9600Hz.
For the calculation, the accuracy of baud-rate depends on truncating (1) or rounding (2) the data.
UA0BRTH regiser and UA0BRTL register have to be set as follows. See the previous secntion 10.3.2. and
section 14.3.2. in UART chapter.
(1) Round data in caluculation
(2) Trancate data in calucuation (the accuracy of baud-rate becomes worse)
UA0BRTH, UA0BRTL = (the frequency ratio of HTBCLK and 9600Hz) - 1 = (N1/128)-1 = N2 -1
N1 = 1011101111110 (binary)
N2 = 101111 (binary) = 47 (decimal) = 2F (hexadecimal)
Set N2-1 (= 2E) to UA0BRTH and UA0BRTL registers.
In this case, the acual baud-rate will be 9595.744681.. [bps], so the accuracy = ((9595.744681/9600) -1)*
100= -0.04..[%].
N1 = 1011101111110 (binary)
N2 = 101110 (binary) = 46 (decimal) = 2E (hexadecimal)
Set N2-1 (= 2D) to UA0BRTH and UA0BRTL registers.
In this case, the acual baud-rate will be 9804.347826.. [bps], so the accuracy = ((9804.347826/9600) -1)*
100= 2.12..[%].
16-bit timer frequency measurement mode application for setting uart baud-rate
N1 = 451000 * 437 / 32768
= 6014 (Decimal)
= 177E (Hexadecimal)
= 1011101111110 (Binary)
Data setting to UA0BRTH register and UA0BRTH register
Round off {N1/4 (2bit right-shift) } - (minus) 1.
Round off {N1/8 (3bit right-shift) } - (minus) 1.
Round off {N1/16 (4bit right-shift) } - (minus) 1.
Round off {N1/32 (5bit right-shift) } - (minus) 1.
Round off {N1/64 (6bit right-shift) } - (minus) 1.
Round off {N1/128 (7bit right-shift) } - (minus) 1.
Round off {N1/256 (8bit right-shift) } - (minus) 1.
Round off {N1/512 (9bit right-shift) } - (minus) 1.
Round off {N1/768} - (minus) 1.
Table 11-6 Baud-rate and theoretical accuracy
10 – 23
ML610Q411/ML610Q412/ML610Q415 User’s Manual
Chapter 10 Timers
Theoretical accuracy
~ +/- 2%
+/- 2% ~ 2.5%
±2.5% ~