HD64336901G Renesas Technology, HD64336901G Datasheet - Page 229

• Manufacturer Part Number: HD64336901G
• Description: (HD64xxx Series) 16-BIT MICROCONTROLLER
• Manufacturer: Renesas Technology

14.3.9
SPMR controls the serial communication function.
Bit
7 to 3
2
1, 0
RXD input signal
Sampling clock
Noise Filter Circuit
The RXD input signal is latched through the noise filter circuit. The noise filter circuit
comprises a series of three latch circuits and a match detection circuit. The RXD input signal is
sampled by the basic clock with the 16 times the transfer clock frequency. If three latch outputs
match, its level is transferred to the next stage. If not, the circuit holds the previous value.
That is, when the incoming signal holds the same level for three clock cycles, it is regarded as
the proper signal. If the levels of the signal is less than three clock cycles, the signal is
regarded as a noise.
Bit Name
STDSPM
Sampling Mode Register (SPMR)
Internal basic clock cycle
Sampling clock
D
Figure 14.2 Block Diagram of Noise Filter Circuit
Initial
Value
All 1
1
All 1
Latch
C
Q
R/W
R/W
D
Latch
C
Q
Description
Reserved
These bits are always read as 1.
Noise Filter Function Select
Selects the noise filter function for the RXD pin in
asynchronous mode.
0: Noise filter circuit is enabled
1: Noise filter circuit is disabled
Reserved
These bits are always read as 1.
D
Latch
C
Q
Match
detection
circuit
Rev. 1.00, 11/03, page 201 of 376
(STDSPM)
SPMR
signal shown
Internal RXD
in figure 14.1