MC812A4CPVE8 Freescale Semiconductor, MC812A4CPVE8 Datasheet - Page 169

• Manufacturer Part Number: MC812A4CPVE8
• Description: IC MCU 16BIT EEPROM 4K 112-LQFP
• Manufacturer: Freescale Semiconductor
• Series: HC12r

Specifications of MC812A4CPVE8

• Core Processor: CPU12
• Core Size: 16-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: POR, WDT
• Number Of I /o: 83
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: EEPROM
• Ram Size: 1K 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: 112-LQFP
• Processor Series: HC812A
• Core: HC12
• Data Bus Width: 16 bit
• Data Ram Size: 1 KB
• Interface Type: SCI, SPI
• Maximum Clock Frequency: 8 MHz
• Number Of Programmable I/os: 91
• Number Of Timers: 8
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8 bit, 8 Channel
• Controller Family/series: 68HC12
• No. Of I/o's: 91
• Eeprom Memory Size: 4KB
• Ram Memory Size: 1KB
• Cpu Speed: 8MHz
• No. Of Timers: 1
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

14.6.2 SCI Control Register 1
Read: Anytime
Write: Anytime
LOOPS — Loop Select Bit
WOMS — Wired-OR Mode Select Bit
RSRC — Receiver Source Bit
Freescale Semiconductor
LOOPS
LOOPS enables loop operation. In loop operation the RXD pin is disconnected from the SCI, and the
transmitter output goes into the receiver input. Both the transmitter and the receiver must be enabled
to use the loop function.
The receiver input is determined by the RSRC bit. The transmitter output is controlled by the
associated DDRS bit.
If the data direction bit for the TXD pin is set and LOOPS = 1, the transmitter output appears on the
TXD pin. If the DDRS bit is clear and LOOPS = 1, the TXD pin is idle (high) if RSRC = 0 and
high-impedance if RSRC = 1. See
WOMS configures the TXD and RXD pins for open-drain operation. WOMS allows TXD pins to be tied
together in a multiple-transmitter system. Then the TXD pins of non-active transmitters follow the logic
level of an active 1. WOMS also affects the TXD and RXD pins when they are general-purpose outputs.
External pullup resistors are necessary on open-drain outputs.
When LOOPS = 1, the RSRC bit determines the internal feedback path for the receiver.
0
1
1
1
1 = Loop operation enabled
0 = Normal operation enabled
1 = TXD and RXD pins, open-drain when outputs
0 = TXD and RXD pins, full CMOS drive capability
1 = Receiver input connected to TXD pin
0 = Receiver input internally connected to transmitter output
RSRC
Reset:
Read:
Write:
SCI0: $00C2
SCI1: $00CA
X
0
0
0
LOOPS
Figure 14-19. SCI Control Register 1 (SC0CR1 or SC1CR1)
Bit 7
DDRSx
0
X
0
1
1
(1)
WOMS
6
0
Table 14-7. Loop Mode Functions
WOMS
MC68HC812A4 Data Sheet, Rev. 7
Table
X
X
0
1
RSRC
5
0
14-7.
Normal operation
Loop mode; transmitter output connected to receiver input
TXD pin disconnected
Loop mode; transmitter output connected to receiver input
TXD is CMOS output
Loop mode; transmitter output connected to receiver input
TXD is open-drain output
M
4
0
WAKE
3
0
Register Descriptions and Reset Initialization
Function of TXD Pin
ILT
2
0
PE
1
0
Bit 0
PT
0
169