Texas Instruments TMS320C3x - Manual (Page 401)

Serial Ports
12-22
12.2.2 FSX/DX/CLKX Port-Control Register
This 32-bit port-control register controls the function of the serial port FSX, DX,
and CLKX pins. The register is shown in Figure 12–14. Table 12–3 shows the
register bits, bit names, and bit functions.
Figure 12–14. FSX/DX/CLKX Port-Control Register
31–16 15–12 11 10 9 8 7 6 5 4 3 2 1 0
xx xx
FSX
DATIN
FSX
DATOUT
FSX
I/O
FSX
FUNC
DX
DATIN
DX
DATOUT
DX
I/O DX
FUNC
CLKX
DATIN
CLKX
DATOUT
CLKX
I/O
CLKX
FUNC
R R/W R/W R/W R R/W R/W R/W R R/W R/W R/W
Notes: 1) R = read, W = write.
2) xx = reserved bit, read as 0.
Table 12–3. FSX/DX/CLKX Port-Control Register Bits Summary
Abbreviation
Reset
Value Name Description
CLKX FUNC 0 Clock transmit
function Controls the function of CLKX.
If CLKX FUNC = 0, CLKX is configured as a general-purpose
digital I/O port.
If CLKX FUNC = 1, CLKX is configured as a serial port pin.
CLKX I/O 0 Clock transmit
input/output
mode If CLKX I/O = 0, CLKX is configured as a general-purpose input
pin.
If CLKX I/O = 1, CLKX is configured as a general-purpose output
pin.
CLKX DATOUT 0 Clock transmit
data ouput Data output on CLKX when configured as general-purpose
output.
CLKX DATIN x † Clock transmit
data input Data input on CLKX when configured as general-purpose input.
A write has no effect.
DX FUNC 0 DX function DXFUNC controls the function of DX.
If DXFUNC = 0, DX is configured as a general-purpose digital
I/O port.
If DXFUNC = 1, DX is configured as a serial port pin.
DX I/O 0 DX input/output
mode If DX I/O = 0, DX is configured as a general-purpose input pin.
If DX I/O = 1, DX is configured as a general-purpose output pin.
DX DATOUT 0 DX data output Data output on DX when configured as general-purpose output.
DX DATIN x † DX data input Data input on DX when configured as general-purpose input.
A write has no effect.
† x = 0 or 1