EM78M611E
Universal Serial Bus Series Microcontroller
high state, then the “high pattern counter“ will increase; otherwise the “low pattern counter” increases. As long as the signal state changes, the PDA will debounce signal and load the value of pattern counter into the respectively register for the firmware to read. For example, if the signal in P.92 is in “low” state, the low counter of P.92 will count continuously until the state of the input signal in P.92 changes. When a state change occurs (in this case, the signal changes from “low” to “high” state), the PDA will take a time break (which is equal to the result of sampling interval multiplied by the debounce length), to avoid possible noise. After the debounce length time, if the signal remains in high state, the high pattern counter will start to count and load the low pattern counter’s value into R10. At the same time, RB[6] is cleared to indicate that low pattern is over.
The correlation between the control register value and debounce time are as follows:
DB.2 |
| DB.1 |
| DB.0 |
0 |
| 0 |
| 0 |
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0 |
| 0 |
| 1 |
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0 |
| 1 |
| 0 |
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0 |
| 1 |
| 1 |
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1 |
| 0 |
| 0 |
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1 |
| 0 |
| 1 |
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1 |
| 1 |
| 0 |
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1 |
| 1 |
| 1 |
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Debounce Time
0
Sampling clock
Sampling clock ⋅ 2
Sampling clock ⋅ 3
Sampling clock ⋅ 4
Sampling clock ⋅ 5
Sampling clock ⋅ 6
Sampling clock ⋅ 7
On the other hand, when the signal of P92 always remains “low”, the low pattern counter of P92 will eventually overflow. Once the counter overflows, the content of the counter will also be loaded into R10, that is, the register is written to 0xFF, and the counter is reset to count from zero again.
If the hardware interrupt of PDA function is enabled, (IOCF[5] is equal to “1”), then the program will go to 0x0001 to execute interrupt routine while the content of a pattern counter is loaded into the register.
The correlation between the value of control register and actual sampling rate are as shown below:
| SR.2 |
| SR.1 |
| SR.0 | Sampling Rate | Sampling Rate | |
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| (External oscillator frequency = 6MHz) | (External oscillator frequency = 12MHz) | ||||
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| 0 |
| 0 |
| 0 | N.A. | N.A. | |
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| 0 |
| 0 |
| 1 | N.A. | N.A. | |
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| 0 |
| 1 |
| 0 | 1500 (Count / mSec) | N.A. | |
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| 0 |
| 1 |
| 1 | 750 (Count / mSec) | 1500 (Count/ mSec) | |
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| 1 |
| 0 |
| 0 | 375 (Count / mSec) | 750 (Count / mSec) | |
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| 1 |
| 0 |
| 1 | 188 (Count / mSec) | 375 (Count / mSec) | |
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| 1 |
| 1 |
| 0 | 94 (Count / mSec) | 188 (Count / mSec) | |
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| 1 |
| 1 |
| 1 | 47 (Count / mSec) | 94 (Count / mSec) | |
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Product Specification (V1.11) 04.20.2007 | • 27 | |||||||
(This specification is subject to change without further notice)