SCI Initialization
Serial Communication Interface (SCI)
8
-7
There are two workarounds for this issue:
n
Enable an SCI pin other than
SCLK
.
n
In the next instruction, enable the remaining SCI pins, including the
SCLK
pin.
Following is an example of one way to initialize the SCI:
1.
Ensure that the SCI is in its individual reset state (PCRE = $0).
2.
Configure the control registers (SCR, SCCR) according to the operating mode, but do not
enable transmitter (TE = 0) or receiver (RE = 0).
Note:
It is now possible to set the interrupts enable bits that are used during the operation.
No interrupt occurs yet.
3.
Enable the SCI by setting the PCRE bits according to which signals are used during operation.
4.
If transmit interrupt is not used, write data to the transmitter.
Note:
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.
5.
Enable transmitters (TE = 1) and receiver (RE = 1) according to use.
Operation starts as follows:
n
For an internally-generated clock, the
SCLK
signal starts operation immediately after
the SCI is enabled (Step 3 above) for Asynchronous modes. In Synchronous mode, the
SCLK
signal is active only while transmitting (that is, a gated clock).
n
Data is received only when the receiver is enabled (RE = 1) and after the occurrence of
the SCI receive sequence on the
RXD
signal, as defined by the operating mode (that is,
idle line sequence).
n
Data is transmitted only after the transmitter is enabled (TE = 1), and after the
initialization sequence has been transmitted (depending on the operating mode).
8.4.1
Preamble, Break, and Data Transmission Priority
Two or three transmission commands can be set simultaneously:
n
A preamble (TE is set.)
n
A break (SBK is set or is cleared.)
n
An indication that there is data for transmission (TDRE is cleared.)
After the current character transmission, if two or more of these commands are set, the
transmitter executes them in the following order: preamble, break, data.
Содержание DSP56303
Страница 1: ...DSP56303 User s Manual 24 Bit Digital Signal Processor DSP56303UM AD Revision 1 January 2001 ...
Страница 52: ...JTAG OnCE Interface 2 22 DSP56303 User s Manual ...
Страница 114: ...General Purpose Input Output GPIO 5 10 DSP56303 User s Manual ...
Страница 212: ...GPIO Signals and Registers 8 26 DSP56303 User s Manual ...
Страница 268: ...Interrupt Equates A 22 DSP56303 User s Manual ...
Страница 306: ...Programming Sheets B 38 DSP56303 User s Manual ...
Страница 320: ...Index 14 DSP56303 User s Manual ...