Sci After Reset; Sci Registers After Reset - Motorola DSP56303 User Manual

8.3

SCI After Reset

There are several different ways to reset the SCI:
n
Hardware
RESET
n
Software RESET instruction:
Both hardware and software resets clear the port control register bits, which
configure all I/O as GPIO input. The SCI remains in the Reset state as long as all
SCI signals are programmed as GPIO (
becomes active only when at least one of the SCI I/O signals is not programmed as
GPIO.
n
Individual reset:
During program execution, the PC2, PC1, and PC0 bits can all be cleared (that is,
individually reset), causing the SCI to stop serial activity and enter the Reset state.
All SCI status bits are set to their reset state. However, the contents of the SCR
remain unaffected so the DSP program can reset the SCI separately from the other
internal peripherals. During individual reset, internal DMA accesses to the data
registers of the SCI are not valid, and the data is unknown.
n
Stop processing state reset (that is, the STOP instruction)
Executing the STOP instruction halts operation of the SCI until the DSP is
restarted, causing the SCI Status Register (SSR) to be reset. No other SCI registers
are affected by the STOP instruction.
Table 8-1 illustrates how each type of reset affects each register in the SCI.
Register Bit Mnemonic
REIE
SCKP
STIR
TMIE
SCR
WOMS
RWU
WAKE
SBK
SSFTD
WDS[2–0]
signal
Table 8-1. SCI Registers After Reset
Bit Number
16
15
14
13
TIE 12
RIE 11
ILIE 10
TE 9
RE 8
7
6
5
4
3
2–0
Serial Communication Interface (SCI)
, , and all are cleared); the SCI
PC2 PC1 PC0
Reset Type
HW Reset SW Reset
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
SCI After Reset
IR Reset ST Reset
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
— —
8-5