ADUC7126 Analog Devices, ADUC7126 Datasheet - Page 61

• Manufacturer Part Number: ADUC7126
• Description: Precision Analog Microcontroller, 12-Bit Analog I/O, Large Memory, ARM7TDMI MCU with Enhanced IRQ Handler
• Manufacturer: Analog Devices

Specifications of ADUC7126

• Mcu Core: ARM7 TDMI
• Mcu Speed (mips): 40
• Gpio Pins: 40
• Adc # Channels: 16
• Other: PWM

Baud Rate Generation
There are two ways of generating the UART baud rate, using
normal 450 UART baud rate generation and using the fractional
divider.
Normal 450 UART Baud Rate Generation
The baud rate is a divided version of the core clock using the value
in the COMDIV0 and COMDIV1 MMRs (16-bit value, DL).
Table 91 gives some common baud rate values.
Table 91. Baud Rate Using the Normal Baud Rate Generator
Baud Rate
9600
19,200
115,200
9600
19,200
115,200
The Fractional Divider
The fractional divider, combined with the normal baud rate
generator, produces a wider range of more accurate baud rates.
Calculation of the baud rate using fractional divider is as follows:
For example, generation of 19,200 baud with CD bits = 3
(Table 91 gives DL = 0x08) is
where:
M = 1.
N = 0.06 × 2048 = 128.
where:
Baud Rate = 19,200 bps.
Baud
Baud
M
M
Baud
M
CLOCK
+
+
+
CORE
2048
2048
2048
Rate
Rate
N
N
N
Rate
÷ (M + N ÷ 2048)
Figure 48. Baud Rate Generation Options
CD
0
0
0
3
3
3
=
=
=
=
=
=
. 1
19
Baud
2
2
÷ 2
2
06
CD
3
CD
,
200
×
41
DL
0x88
0x44
0x0B
0x11
0x08
0x01
×
16
×
41
.
16
41
78
Rate
16
×
×
.
78
2
.
8
MHz
×
×
78
41
3
×
41
2
DL
MHz
FBEN
×
×
2
MHz
×
.
Actual Baud Rate
9600
19,200
118,691
9600
20,400
163,200
78
16
.
×
78
2
DL
×
CD



×
MHz
2
MHz
2048
×
8
128
×
×



M
16
2
÷ 16DL



+
×
DL
2048
N
×
2



UART
% Error
0
0
3
0
6.25
41.67
Rev. B | Page 61 of 104
Error is 0%, compared to 6.25% with the normal baud rate
generator.
UART Register Definitions
COM0TX Register
Name:
Address:
Default Value:
Access:
COM0TX is an 8-bit transmit register for UART0.
COM1TX Register
Name:
Address:
Default Value:
Access:
COM1TX is an 8-bit transmit register for UART1.
COM0RX Register
Name:
Address:
Default Value:
Access:
COM0RX is an 8-bit receive register for UART0.
COM1RX Register
Name:
Address:
Default Value:
Access:
COM1RX is an 8-bit receive register for UART1.
COM0DIV0 Register
Name:
Address:
Default Value:
Access:
COM0DIV0 is a low byte divisor latch for UART0. COM0TX,
COM0RX, and COM0DIV0 share the same address location.
COM0TX and COM0RX can be accessed when Bit 7 in the
COM0CON0 register is cleared. COM0DIV0 can be accessed
when Bit 7 of COM0CON0 is set.
ADuC7124/ADuC7126
COM1TX
0xFFFF0740
0x00
Read/write
COM0RX
0xFFFF0700
0x00
Read only
COM1RX
0xFFFF0740
0x00
Read only
COM0DIV0
0xFFFF0700
0x00
Read/write
COM0TX
0xFFFF0700
0x00
Read/write