MC68376BGMAB20 Freescale Semiconductor, MC68376BGMAB20 Datasheet - Page 177

• Manufacturer Part Number: MC68376BGMAB20
• Description: IC MCU 32BIT 8K ROM 160-QFP
• Manufacturer: Freescale Semiconductor
• Series: M683xxr

Specifications of MC68376BGMAB20

• Core Processor: CPU32
• Core Size: 32-Bit
• Speed: 20MHz
• Connectivity: CAN, EBI/EMI, SCI, SPI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Type: ROMless
• Ram Size: 7.5K x 8
• Voltage - Supply (vcc/vdd): 4.75 V ~ 5.25 V
• Data Converters: A/D 16x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 160-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

MC68336/376
USER’S MANUAL
Data to be transmitted is written to SCDR, then transferred to the serial shifter. The
transmit data register empty (TDRE) flag in SCSR shows the status of TDR. When
TDRE = 0, the TDR contains data that has not been transferred to the shifter. Writing
to SCDR again overwrites the data. TDRE is set when the data in the TDR is trans-
ferred to the shifter. Before new data can be written to the SCDR, however, the pro-
cessor must clear TDRE by writing to SCSR. If new data is written to the SCDR without
first clearing TDRE, the data will not be transmitted.
The transmission complete (TC) flag in SCSR shows transmitter shifter state. When
TC = 0, the shifter is busy. TC is set when all shifting operations are completed. TC is
not automatically cleared. The processor must clear it by first reading SCSR while TC
is set, then writing new data to SCDR.
The state of the serial shifter is checked when the TE bit is set. If TC = 1, an idle frame
is transmitted as a preamble to the following data frame. If TC = 0, the current opera-
tion continues until the final bit in the frame is sent, then the preamble is transmitted.
The TC bit is set at the end of preamble transmission.
The SBK bit in SCCR1 is used to insert break frames in a transmission. A non-zero
integer number of break frames is transmitted while SBK is set. Break transmission
begins when SBK is set, and ends with the transmission in progress at the time either
SBK or TE is cleared. If SBK is set while a transmission is in progress, that transmis-
sion finishes normally before the break begins. To assure the minimum break time,
toggle SBK quickly to one and back to zero. The TC bit is set at the end of break trans-
mission. After break transmission, at least one bit-time of logic level one (mark idle) is
transmitted to ensure that a subsequent start bit can be detected.
If TE remains set, after all pending idle, data and break frames are shifted out, TDRE
and TC are set and TXD is held at logic level one (mark).
When TE is cleared, the transmitter is disabled after all pending idle; data and break
frames are transmitted. The TC flag is set, and control of the TXD pin reverts to
PQSPAR and DDRQS. Buffered data is not transmitted after TE is cleared. To avoid
losing data in the buffer, do not clear TE until TDRE is set.
Some serial communication systems require a mark on the TXD pin even when the
transmitter is disabled. Configure the TXD pin as an output, then write a one to PQS7.
When the transmitter releases control of the TXD pin, it reverts to driving a logic one
output.
To insert a delimiter between two messages, to place non-listening receivers in wake-
up mode between transmissions, or to signal a retransmission by forcing an idle line,
clear and then set TE before data in the serial shifter has shifted out. The transmitter
finishes the transmission, then sends a preamble. After the preamble is transmitted, if
TDRE is set, the transmitter will mark idle. Otherwise, normal transmission of the next
sequence will begin.
Both TDRE and TC have associated interrupts. The interrupts are enabled by the
transmit interrupt enable (TIE) and transmission complete interrupt enable (TCIE) bits
in SCCR1. Service routines can load the last byte of data in a sequence into SCDR,
then terminate the transmission when a TDRE interrupt occurs.
QUEUED SERIAL MODULE
MOTOROLA
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