DSP56309EVM Freescale Semiconductor, DSP56309EVM Datasheet - Page 174

• Manufacturer Part Number: DSP56309EVM
• Description: KIT EVALUATION FOR XC56309
• Manufacturer: Freescale Semiconductor
• Type: DSPr

Specifications of DSP56309EVM

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Description/function: Audio DSPs
• Product: Audio Modules
• For Use With/related Products: DSP56309
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Serial Communication Interface (SCI)
8.4 SCI Initialization
The SCI is initialized as follows:
If interrupts are to be used, the signals must be selected, and global interrupts must be enabled
and unmasked before the SCI can operate. The order does not matter; any one of these three
requirements for interrupts can enable the SCI, but the interrupts should be unmasked last (that is,
I[1–0] bits in the Status Register (SR) should be changed last). Synchronous applications usually
require exact frequencies, so the crystal frequency must be chosen carefully. An alternative to
selecting the system clock to accommodate the SCI requirements is to provide an external clock
to the SCI. When the SCI is configured in Synchronous mode, internal clock, and all the SCI pins
are simultaneously enabled, an extra pulse of one DSP clock length is provided on the
There are two workarounds for this issue:
Following is an example of one way to initialize the SCI:
Note:
Note:
8-6
1.
2.
3.
1.
2.
3.
4.
5.
Enable an SCI pin other than
In the next instruction, enable the remaining SCI pins, including the
Ensure that the SCI is in its individual reset state (PCRE = $0). Use a hardware
signal or software RESET instruction.
Program the SCI control registers.
Configure at least one SCI signal as an SCI signal.
Ensure that the SCI is in its individual reset state (PCRE = $0).
Configure the control registers (SCR, SCCR) according to the operating mode, but do
not enable transmitter (TE = 0) or receiver (RE = 0).
Enable the SCI by setting the PCRE bits according to which signals are used during
operation.
If transmit interrupt is not used, write data to the transmitter.
Enable transmitters (TE = 1) and receiver (RE = 1) according to use.
It is now possible to set the interrupts enable bits that are used during the operation. No
interrupt occurs yet.
If transmitter interrupt enable is set, an interrupt is issued and the interrupt handler
should write data into the transmitter. The DMA channel services the SCI transmit
request if it is programmed to service the SCI transmitter.
DSP56309 User’s Manual, Rev. 1
SCLK
.
SCLK
Freescale Semiconductor
pin.
SCLK
RESET
pin.