MC68HC705B16CFN Freescale Semiconductor, MC68HC705B16CFN Datasheet - Page 91

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MC68HC705B16CFN

Manufacturer Part Number
MC68HC705B16CFN
Description
IC MCU 2.1MHZ 15K OTP 52-PLCC
Manufacturer
Freescale Semiconductor
Series
HC05r
Datasheet

Specifications of MC68HC705B16CFN

Core Processor
HC05
Core Size
8-Bit
Speed
2.1MHz
Connectivity
SCI
Peripherals
POR, WDT
Number Of I /o
32
Program Memory Size
15KB (15K x 8)
Program Memory Type
OTP
Eeprom Size
256 x 8
Ram Size
352 x 8
Voltage - Supply (vcc/vdd)
4.5 V ~ 5.5 V
Data Converters
A/D 8x8b
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
Table 6-5 Second prescaler stage (receiver)
SCR2
0
0
0
0
1
1
1
1
The following equations are used to calculate the receiver and transmitter baud rates:
where:
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
= oscillator frequency
OSC
6.12
Baud rate selection
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.
Table 6-6
shows the baud rates that can be achieved, for five typical crystal
frequencies. These are effectively the highest baud rates which can be achieved using a given
crystal.
MC68HC05B6
SERIAL COMMUNICATIONS INTERFACE
Rev. 4.1
Table
6-5.
Receiver
SCR1
SCR0
division ratio (NR)
0
0
1
0
1
2
1
0
4
1
1
8
0
0
16
0
1
32
1
0
64
1
1
128
f
op
=
---------------------------------- -
baudTx
16 NP NT
f
op
=
baudRx
-----------------------------------
16 NP NR
6
Freescale
6-19

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