Typewriter User Manual

7- 22 MC68340 USER’S MANUAL MOTOROLA
IVR $705
76543210
IVR7 IVR6 IVR5 IVR4 IVR3 IVR2 IVR1 IVR0
RESET:
00001111
Read /Write Supervisor Only
IVR7–IVR0—Interrupt Vector Bits
Each module that generates interrupts has an interrupt vector field. This 8-bit number
indicates the offset from the base of the vector table where the address of the exception
handler for the specified interrupt is located. The IVR is reset to $0F, which indicates an
uninitialized interrupt condition. See Section 5 CPU32 for more information.
7.4.1.4 MODE REGISTER 1 (MR1). MR1 controls some of the serial module
configuration. This register can be read or written at any time when the serial module is
enabled (i.e., the STP bit in the MCR is cleared).
MR1A, MR1B $710, $718
76543210
RxRTS R/F ERR PM1 PM0 PT B/C1 B/C0
RESET:
00000000
Read/Write Supervisor/User
RxRTS—Receiver Request-to-Send Control
1 = Upon receipt of a valid start bit,
RTS≈ is negated if the channel's FIFO is full.
RTS≈ is reasserted when the FIFO has an empty position available.
0 =
RTS≈ is asserted by setting bit 1 or 0 in the OP and negated by clearing bit 1 or
0 in the OP.
This feature can be used for flow control to prevent overrun in the receiver by using the
RTS≈ output to control the CTS≈ input of the transmitting device. If both the receiver
and transmitter are programmed for
RTS control, RTS control will be disabled for both
since this configuration is incorrect. See 7.4.1.17 Mode Register 2 for information on
programming the transmitter
RTS≈ control.
R/F—Receiver-Ready Select
1 = Bit 5 for channel B and bit 1 for channel A in the ISR reflect the channel FIFO full
status. These ISR bits are set when the receiver FIFO is full and are cleared
when a position is available in the FIFO.
0 = Bit 5 for channel B and bit 1 for channel A in the ISR reflect the channel receiver-
ready status. These ISR bits are set when a character has been received and are
cleared when the CPU32 reads the receive buffer.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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