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Basic Information
Functional Description
Application Description
Question 1
Under what operating voltage does the HT82A525R work?
Answer
In addition to the standard USB operating voltage, the HT82A525R can be operated at a voltage of 3.3V~5.5V with an operating frequency of 6MHZ, and also at 4.5V~5.5V at 12 MHZ. Additionally a VDDIO function is provided for variable I/O output voltages to allow the HT82A525R to have more flexible output control for external devices.
Question 2
How do I use the Parallel DMA in the HT82A525R?
Answer
When the Parallel DMA is enabled, the HT82A525R will save the DMA data through ENDPOINT 2. However the FIFO2 and FIFO3 buffer will be used so do not manually save the FIFO2 and FIFO3 buffer. The PDMA control bit controls the on and off function of the Parallel DMA which uses the PD0~PD7 bits to receive or transmit data. When the Parallel DMA is in use, the Serial DMA will be invalid.
Question 3
How do I use the Serial DMA in the HT82A525R?
Answer
When the Serial DMA is enabled, the HT82A525R will save DMA data through ENDPOINT 3. The FIFO3 buffer will be used, so when the Serial DMA is enabled, do not save the FIFO3 buffer manually. The SDMAEN control bit controls the on and off function of the Serial DMA. The CLKAUTOB control bit can control whether the Serial DMA should be automatically disabled after the buffer is full. The SDMASEL control bit can select if the first or second SPI function is to be used. When the Serial DMA is in use, the Parallel DMA will be invalid.
Question 4
How does the HT82A525R acquire image with a CMOS sensor?
Answer
The HT82A525R can acquire image values from most CMOS sensors mainly by using the Parallel DMA function to switch PDMA_MOD to FINGERPRINT MODE first, and then respectively connect PCLK of the CMOS sensor to PA5, HSYNC to PA4 and VSYNC to PA0. The MCU will sync the data value according to the above setting after PCLK, VSYNC and HSYNC are enabled from the option menu.
Due to different sensor characteristics, the image format can be QVGA (320X240) or CIF (352_288) selected by FIG_PIX while the PDATA_SEL can decide if DMA data of odd numbers or all data is to be acquired. The Parallel DMA data length in the option can decide if 8 or 5-bit data to be acquired each time. To accompany the YUV format of the sensor, acquiring the 5-bit data only from the vector Y can enhance the data saving speed.
Points to Note
Question 1
When using the HIRC, if the I/O pin which is shared with OSC1 is to be used as an AC zero crossing detector, will there be any influence on the HIRC oscillation frequency? If yes, which MCUs will be affected and how can this problem be resolved?? Answer
If the HIRC is used and if the I/O pin which is shared with OSC1 is used as an AC zero crossing detector pin, the HIRC oscillation frequency will be influenced.
The affected MCUs are:
All MCUs whose I/O pin is pin-shared with OSC1 (including the enhanced OTP type MCU and Flash type MCU etc.)
How to resolve this issue:
1. Avoid using the I/O pin that is shared with OSC1 as AC zero crossing detector pin.
2. If the problem can still not be resolved, add external circuitry to ensure that the voltage applied on the OSC1 pin remains withing the range of VDD and VSS.
Others
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