EM6607 EM Microelectronic, EM6607 Datasheet - Page 26

• Manufacturer Part Number: EM6607
• Description: Ultra-low power microcontroller
• Manufacturer: EM Microelectronic

12 Serial Write Buffer – SWB
The EM6607 has a simple Serial Write Buffer (SWB) which outputs serial data and serial clock.
The SWB is enabled by setting the bit V03 in the CLKSWB register as well as setting port D to output mode. The
combination of the possible PortD mode is shown in Table 34. In SWB mode the serial clock is output on port D0 and the
serial data is output on port D1.
The signal TestVar[3], which is used by the processor to make conditional jumps, indicates "Transmission finished" in
automatic send mode or "SWBbuffer empty" in interactive send mode. In interactive mode, TestVar[3] (see port A section) is
equivalent to the interrupt request flags stored in IntRq register : it permits to recognise the interrupt source. (See also the
interrupt handling section 9.Interrupt Controller for further information). To serve the "SWBbuffer empty " interrupt request,
one only has to make a conditional jump on TestVar[3].
Bits ClkSWB0 and ClkSWB1 in the ClkSWB register select the Serial Write Buffer output clock frequency. The
possible values are 1kHz (default), 2kHz, 8kHz or 16kHz and are shown in Table below:
Table 40.
Table 41.
Table 42.
When the SWB is enabled by setting the bit V03 TestVar[3], which is used to make conditional jumps, is reassigned to the
SWB and indicates either "SWBbuffer empty " interrupt or "Transmission finished" . After Power-on-RESET V03 is cleared
at "0" and TestVar[3] is consequently assigned to PA2 input terminal.
The SWB data is output on the rising edge of the clock. Consequently, on the receiver side the serial data can be evaluated
on falling edge of the serial clock edge.
Copyright © 2005, EM Microelectronic-Marin SA
PortD status
« NORMAL »
« NORMAL »
« NORMAL »
« SWB »
Bit
3
2
1
0
SWB clock output
1024 Hz
2048 Hz
8192 Hz
16384 Hz
SWB clock selection
SWB clock selection register - ClkSWB
PortD status
R
Name
V03
CkSWB1
CkSWB0
-
CIOPD
0
0
1
1
CkSWB1
0
0
1
1
V03
0
1
0
1
Reset
0
0
0
0
input
input
output PD0
serial clock Out
PD0
CkSWB0
0
1
0
1
R/W
R/W
R
R/W
R/W
SWB serial data
input
input
output PD1
PD1
Description
Serial Write buffer selection
SWB clock selector 1
SWB clock selector 0
RESERVED - read 0
26
PD2
output PD2
output PD2
input
input
PD3
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input
input
output PD3
output PD3
EM6607