XC68HC705B32CFN Freescale Semiconductor, XC68HC705B32CFN Datasheet - Page 91

• Manufacturer Part Number: XC68HC705B32CFN
• Description: IC MCU 2.1MHZ 32K OTP 52-PLCC
• Manufacturer: Freescale Semiconductor
• Series: HC05r

Specifications of XC68HC705B32CFN

• Core Processor: HC05
• Core Size: 8-Bit
• Speed: 2.1MHz
• Connectivity: SCI
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: OTP
• Eeprom Size: 256 x 8
• Ram Size: 528 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x8b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 52-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

SCR2, SCR1, SCR0 — SCI rate select bits (receiver)
These three read/write bits select the baud rates for the receiver. The prescaler output described
above is divided by the factors shown in
The following equations are used to calculate the receiver and transmitter baud rates:
where:
6.12
The flexibility of the baud rate generator allows many different baud rates to be selected. A
particular baud rate may be generated in several ways by manipulating the various prescaler and
division ratio bits.
frequencies. These are effectively the highest baud rates which can be achieved using a given
crystal.
MC68HC05B6
Rev. 4.1
NP = prescaler divide ratio
NT = transmitter baud rate divide ratio
NR = receiver baud rate divide ratio
baudTx = transmitter baud rate
baudRx = receiver baud rate
f
OSC
= oscillator frequency
Baud rate selection
Table 6-6
Table 6-5 Second prescaler stage (receiver)
SERIAL COMMUNICATIONS INTERFACE
SCR2
shows the baud rates that can be achieved, for five typical crystal
0
0
0
0
1
1
1
1
baudRx
baudTx
SCR1
0
0
1
1
0
0
1
1
Table
=
=
6-5.
SCR0
---------------------------------- -
16 NP NT
-----------------------------------
16 NP NR
0
1
0
1
0
1
0
1
•
•
f
f
op
op
•
•
division ratio (NR)
Receiver
128
16
32
64
1
2
4
8
Freescale
6-19
6