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8XC196NT USER’S MANUAL
8-14
Figure 8-7. Variable-width MSB in SSIO Transmissions
NOTE
This condition exists only for the MSB. Once the MSB is clocked out, the
remaining bits are clocked out consistently at the programmed frequency.
One way to achieve a consistent MSB bit length is to start the down-count at a fixed time, using
these steps:
1.
Clear SSIO_BAUD bit 7. This disables the baud-rate generator and clears the remaining
bits (BV6:0).
2.
Write the byte to be transmitted to SSIOx_BUF.
3.
Set the STE bit in SSIOx_CON. This enables transfers and drives the MSB onto the data
pin.
4.
Disable interrupts.
5.
Set the MSB of SSIO_BAUD and write the desired BAUD_VAL to the remaining bits.
This enables the baud-rate generator and starts the down count.
6.
Rewrite the byte to be transmitted to SSIOx_BUF. This starts the transmission.
7.
Enable interrupts.
Using this procedure starts the clock at a known point before each transmission, establishing a
predictable MSB bit time. Interrupts are disabled in step 4 and reenabled in step 7; otherwise, an
interrupt could cause a similar problem between steps 5 and 6.
Clock (SC
x pin)
Data (SD
x pin)
1
2
3
4
"1"
MSB
B6
B5
B4
B3
"0"
"1"
"0"
"0"
A2066-01
Содержание 8XC196NT
Страница 1: ...8XC196NT Microcontroller User s Manual...
Страница 2: ...8XC196NT Microcontroller User s Manual June 1995 Order Number 272317 003...
Страница 22: ...1 Guide to This Manual...
Страница 23: ......
Страница 35: ......
Страница 36: ...2 Architectural Overview...
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Страница 49: ......
Страница 50: ...3 Programming Considerations...
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Страница 66: ...4 Memory Partitions...
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Страница 104: ...5 Standard and PTS Interrupts...
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Страница 147: ......
Страница 148: ...6 I O Ports...
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Страница 176: ...7 Serial I O SIO Port...
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Страница 194: ...8 Synchronous Serial I O SSIO Port...
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Страница 212: ...9 Slave Port...
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Страница 232: ...10 Event Processor Array EPA...
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Страница 270: ...11 Analog to digital Converter...
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Страница 292: ...12 Minimum Hardware Considerations...
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Страница 306: ...13 Special Operating Modes...
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Страница 318: ...14 Interfacing with External Memory...
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Страница 362: ...15 Programming the Nonvolatile Memory...
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Страница 408: ...A Instruction Set Reference...
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Страница 476: ...B Signal Descriptions...
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Страница 494: ...C Registers...
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Страница 566: ...Glossary...
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Страница 580: ...Index...
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