COP8CCR9IMT7/NOPB National Semiconductor, COP8CCR9IMT7/NOPB Datasheet - Page 50

• Manufacturer Part Number: COP8CCR9IMT7/NOPB
• Description: IC MCU EEPROM 8BIT 32K 48-TSSOP
• Manufacturer: National Semiconductor
• Series: COP8™ 8Cr

Specifications of COP8CCR9IMT7/NOPB

• Core Processor: COP8
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: Microwire/Plus (SPI), UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 39
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 16x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 48-TSSOP
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 20 MHz
• Data Ram Size: 1 KB
• On-chip Adc: 10 bit, 16 channel
• Number Of Programmable I/os: 59
• Number Of Timers: 3
• Height: 0.9 mm
• Interface Type: SPI, USART
• Length: 12.5 mm
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 4.5 V
• Width: 6.1 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details
• Other names: *COP8CCR9IMT7; *COP8CCR9IMT7/NOPB; COP8CCR9IMT7

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14.0 USART
many ways to calculate the two divisor factors, but one
particularly effective method would be to achieve a 1.8432
MHz frequency coming out of the first stage. The 1.8432
MHz prescaler output is then used to drive the software
programmable baud rate counter to create a 16x clock for
the following baud rates: 110, 134.5, 150, 300, 600, 1200,
1800, 2400, 3600, 4800, 7200, 9600, 19200 and 38400
(Table 17). Other baud rates may be created by using ap-
propriate divisors. The 16x clock is then divided by 16 to
provide the rate for the serial shift registers of the transmitter
and receiver.
Note: The entries in Table 17 assume a prescaler output of 1.8432 MHz. In
asynchronous mode the baud rate could be as high as 1250k.
FIGURE 24. USART BAUD Clock Generation
134.5 (134.58)
110 (110.03)
Baud Rate
TABLE 17. Baud Rate Divisors
(1.8432 MHz Prescaler Output)
TABLE 18. Prescaler Factors
19200
38400
1200
1800
2400
3600
4800
7200
9600
Prescaler
150
300
600
Select
00000
00001
00010
00011
00100
00101
00110
00111
(Continued)
Divisor − 1 (N-1)
NO CLOCK
Prescaler
Baud Rate
Factor
1.5
2.5
3.5
1046
855
767
383
191
1
2
3
4
95
63
47
31
23
15
11
5
2
10137427
50
As an example, considering Asynchronous Mode and a crys-
tal frequency of 4.608 MHz, the prescaler factor selected is:
The 5 entry is available in Table 18. The 1.8432 MHz pres-
caler output is then used with proper Baud Rate Divisor
(Table 17) to obtain different baud rates. For a baud rate of
19200 e.g., the entry in Table 17 is 5.
The divide by 16 is performed because in the asynchronous
mode, the input frequency to the USART is 16 times the
baud rate. The equation to calculate baud rates is given
below.
The actual Baud Rate may be found from:
Where:
BR is the Baud Rate
F
N is the Baud Rate Divisor (Table 17)
P is the Prescaler Divide Factor selected by the value in the
Prescaler Select Register (Table 18)
Note: In the Synchronous Mode, the divisor 16 is replaced
by two.
Example:
Asynchronous Mode:
C
N − 1 = 5 (N − 1 is the value from Table 17)
N = 6 (N is the Baud Rate Divisor)
Baud Rate = 1.8432 MHz/(16 x 6) = 19200
BR = (F
Crystal Frequency = 5 MHz
Desired baud rate = 19200
is the crystal frequency
C
x 2)/(16 x N x P)
Prescaler
Select
01000
01001
01010
01011
01100
01101
10000
10001
10010
10011
10100
10101
10110
11000
11001
11010
01110
01111
10111
11011
11100
11101
11110
(4.608 x 2)/1.8432 = 5
11111
Prescaler
Factor
10.5
11.5
12.5
13.5
14.5
15.5
4.5
5.5
6.5
7.5
8.5
9.5
10
11
12
13
14
15
16
5
6
7
8
9