Functional Description
Question 1
When using the tools to change the value of bits in the PA port register from "0" to "1", why when after checking the content of the register, I cannot see that the PA pin has changed its value.
Answer
When changing a specific bit value on the PA data register, only bits that are setup as outputs will be changed. Bits to be changed must first be setup as outputs by writing a zero to the corresponding bit of the PAC register.
Application Description
Question 1
Can Endpoint 0 in the HT82M99E be an INPUT PIPE?
Answer
Endpoint 0 in the HT82M99E can only be used to control transmission, however HID type GETREPORT can be used in Endpoint 0 to obtain data.
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
Question 1
In an application example, “Using the HT82M99E to implement an RS232 to USB interface converter”, why does the USB bus send an error and the oscillator in the HT82M99E stop running?
Answer
In this example, after the USB bus sends an error, the USB bus will enter the suspend mode. At this time the program will jump to the HALT instruction, which after execution will place the MCU into the Power-down mode, where the oscillator stops running.
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