MC68HC711E20CFN2

Manufacturer Part NumberMC68HC711E20CFN2
DescriptionIC MCU 20K 2MHZ OTP 52-PLCC
ManufacturerFreescale Semiconductor
SeriesHC11
MC68HC711E20CFN2 datasheets
 

Specifications of MC68HC711E20CFN2

Core ProcessorHC11Core Size8-Bit
Speed2MHzConnectivitySCI, SPI
PeripheralsPOR, WDTNumber Of I /o38
Program Memory Size20KB (20K x 8)Program Memory TypeOTP
Eeprom Size512 x 8Ram Size768 x 8
Voltage - Supply (vcc/vdd)4.5 V ~ 5.5 VData ConvertersA/D 8x8b
Oscillator TypeInternalOperating Temperature-40°C ~ 85°C
Package / Case52-PLCCLead Free Status / RoHS StatusContains lead / RoHS non-compliant
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Figure 2
shows how the bootloader program differentiates between the default baud rate (7812 baud at
a 2-MHz E-clock rate) and the alternate baud rate (1200 baud at a 2-MHz E-clock rate). The host
computer sends an initial $FF character, which is used by the bootloader to determine the baud rate that
will be used for the downloading operation. The top half of
Receive data samples at [1] detect the falling edge of the start bit and then verify the start bit by taking a
sample at the center of the start bit time. Samples are then taken at the middle of each bit time [2] to
reconstruct the value of the received character (all 1s in this case). A sample is then taken at the middle
of the stop bit time as a framing check (a 1 is expected) [3]. Unless another character immediately follows
this $FF character, the receive data line will idle in the high state as shown at [4].
The bottom half of
Figure 2
shows how the receiver will incorrectly receive the $FF character that is sent
from the host at 1200 baud. Because the receiver is set to 7812 baud, the receive data samples are taken
at the same times as in the upper half of
the start bit at 7812 baud [6].
$0000
$01FF
EXTERNAL
$1000
$103F
EXTERNAL
$B600
$B7FF
EXTERNAL
$BF00
$BFC0
$BFFF
$D000
$FFC0
$FFFF
SINGLE
EXPANDED
CHIP
MULTIPLEXED
MODA = 0
MODA = 1
MODB = 1
MODB = 1
NOTE: Software can change some aspects of the memory map after reset.
Figure 1. MC68HC711E9 Composite Memory Map
Freescale Semiconductor
Figure 2
Figure
2. The start bit at 1200 baud [5] is 6.5 times as long as
EXTERNAL
EXTERNAL
EXTERNAL
SPECIAL
SPECIAL
BOOTSTRAP
TEST
MODA = 0
MODA = 1
MODB = 0
MODB = 0
M68HC11 Bootstrap Mode, Rev. 1.1
Automatic Selection of Baud Rate
shows normal reception of $FF.
(MAY BE REMAPPED
TO ANY 4K BOUNDARY)
512-BYTE
RAM
64-BYTE
(MAY BE REMAPPED
TO ANY 4K BOUNDARY)
REGISTER
BLOCK
(MAY BE DISABLED
512-BYTE
BY AN EEPROM BIT)
EEPROM
$BFC0
BOOT
SPECIAL
ROM
MODE
VECTORS
$BFFF
(MAY BE DISABLED
BY AN EEPROM BIT)
12K USER
EPROM
$FFC0
(or OTP)
NORMAL
MODE
VECTORS
$FFFF
197