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Points to Note
Question 1
For the pull-high resistors on the HT46R0x input and output lines are there any special points to note?
Answer
Pins PA0~PA6 in the HT46R0x series can both function as input or output pins while PA7 can only be used as an input line. With the exception of PA7, all the other pins can select a pull high resister. The difference between this device and most of the other Holtek devices, is that the pull high resistors are not selected using configuration options but instead use an internal PAPU register for their selection. As PA7 does not have a pull-high option an external resistor must be connected if it requires a pull-high function.
Question 2
In the HT46R0x series of microcontrollers, what points need to be noted regarding the A/D converter clock source?
Answer
The A/D converter clock source is a division of the system clock source, the division ratio of which is controlled using the ACSR register bits ADCS2~ADCS0. However because the A/D converter clock period must not be less than 1us, when the system clock is greater than 1MHz, if the ADCS2~ADCS0 bits permit a clock period of less than 1us, then this will create inaccurate A/D conversion values. For this reason care must be taken with the division ratio for system clock frequencies in excess of 1MHz to ensure that an A/D clock period of not less than 1us is obtained. The following table can be used for consultation. Values with an upper case start are not permitted.
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