SERIAL COMMUNICATION INTERFACE (SCI)
MOTOROLA
PORT C
6 - 21
6.3.2.1.10
SCR SCI Receive Interrupt Enable (RIE) Bit 11
The RIE bit is used to enable the SCI receive data interrupt. If RIE is cleared, receive in-
terrupts are disabled, and the RDRF bit in the SCI status register must be polled to deter-
mine if the receive data register is full. If both RIE and RDRF are set, the SCI will request
an SCI receive data interrupt from the interrupt controller.
One of two possible receive data interrupts will be requested:
1. Receive without exception will be requested if PE, FE, and OR are all clear
(i.e., a normal received character).
2. Receive with exception will be requested if PE, FE, and OR are not all clear
(i.e., a received character with an error condition).
RIE is cleared by hardware and software reset.
6.3.2.1.11
SCR SCI Transmit Interrupt Enable (TIE) Bit 12
The TIE bit is used to enable the SCI transmit data interrupt. If TIE is cleared, transmit
data interrupts are disabled, and the transmit data register empty (TDRE) bit in the SCI
status register must be polled to determine if the transmit data register is empty. If both
TIE and TDRE are set, the SCI will request an SCI transmit data interrupt from the inter-
rupt controller. TIE is cleared by hardware and software reset.
6.3.2.1.12
SCR Timer Interrupt Enable (TMIE) Bit 13
The TMIE bit is used to enable the SCI timer interrupt. If TMIE is set (enabled), the timer
interrupt requests will be made to the interrupt controller at the rate set by the SCI clock
register. The timer interrupt is automatically cleared by the timer interrupt acknowledge
from the interrupt controller. This feature allows DSP programmers to use the SCI baud
clock generator as a simple periodic interrupt generator if the SCI is not in use, if external
clocks are used for the SCI, or if periodic interrupts are needed at the SCI baud rate. The
SCI internal clock is divided by 16 (to match the 1
×
SCI baud rate) for timer interrupt gen-
eration. This timer does not require that any SCI pins be configured for SCI use to operate.
TMIE is cleared by hardware and software reset.
6.3.2.1.13
SCR SCI Timer Interrupt Rate (STIR) Bit 14
This bit controls a divide by 32 in the SCI Timer interrupt generator. When this bit is
cleared, the divide by 32 is inserted in the chain. When the bit is set, the divide by 32 is
bypassed, thereby increasing the timer resolution by 32 times. This bit is cleared by hard-
ware and software reset.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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