Switchover Between Analog Input And General Port Functions - Hitachi SH7032 Hardware Manual

Note: All figures are reference values.
Table 14.5 Analog Input Pin Ratings
Item
Analog input capacitance
Allowable signal-source impedance
14.7.3

Switchover between Analog Input and General Port Functions

1. Switchover to/from general port function
When the A/D converter is started by setting the A/D start bit (ADST) to 1 in the A/D
control/status register (ADCSR), or by asserting the _ADTRG pin, port C pins begin
functioning as analog input pins (ANn). When A/D conversion ends, the pins are switched
back to the general port (digital input) function.
2. Port C pins not used for A/D conversion
Pins not selected as AN pins by the channel select setting can be used in the following
combinations as general port pins in both single mode and scan mode.
(a) When any or all of pins AN0 to AN3 are used for A/D conversion, AN4 to AN7 can be
used as general port pins.
(b) When any or all of pins AN4 to AN7 are used for A/D conversion, AN0 to AN3 can be
used as general port pins.
424
AN0–AN7
Analog multiplexer
A/D converter
Figure 14.9 Analog Input Pin Equivalent Circuit
1.0 kΩ
20 pF
Min Max
— 20
— 3
1 MΩ
Unit
pF
kΩ