User's Manual
Table Of Contents
- GC864 Hardware User Guide
- APPLICABILITY TABLE
- 1. Introduction
- 2. Overview
- 3. GC864 Mechanical Dimensions
- 4. GC864-QUAD/PY Module Connections
- 5. Hardware Commands
- 6. Power Supply
- 7. Antenna
- 8. Logic Level Specifications
- 9. Serial Ports
- 10. Audio Section Overview
- 11. General Purpose I/O
- 11.1. GPIO Logic Levels
- 11.2. Using a GPIO Pad as INPUT
- 11.3. Using a GPIO Pad as OUTPUT
- 11.4. Using the RF Transmission Control GPIO4
- 11.5. Using the RFTXMON Output GPIO5
- 11.6. Using the Alarm Output GPIO6
- 11.7. Using the Buzzer Output GPIO7
- 11.8. Magnetic Buzzer Concepts
- 11.9. Using the Temperature Monitor Function
- 11.10. Indication of Network Service Availability
- 11.11. RTC Bypass Out
- 11.12. VAUX1 Power Output
- 12. DAC and ADC Section
- 13. Mounting the GC864-QUAD/PY on the Board
- 14. Packing System
- Conformity Assessment Issues
GC864 Hardware User Guide
1vv0300733 Rev.12 – 2009-06-04
11.1. GPIO Logic Levels
Where not specifically stated, all the interface circuits work at 2.8V CMOS logic
levels.
The following tables show the logic level specifications used in the GC864-QUAD/PY
interface circuits:
Absolute Maximum Ratings –Not Functional
Parameter Min Max
Input level on any
digital pin when on
-0.3V +3.6V
Input voltage on
analog pins when on
-0.3V +3.0 V
Operating Range – Interface Levels (2.8V CMOS)
Level Min Max
Input high level 2.1V 3.3V
Input low level 0V 0.5V
Output high level 2.2V 3.0V
Output low level 0V 0.35V
For 1.8V signals:
Operating Range – Interface Levels (1.8V CMOS)
Level Min Max
Input high level 1.6V 2.2V
Input low level 0V 0.4V
Output high level 1,65V 2.2V
Output low level 0V 0.35V
11.2. Using a GPIO Pad as INPUT
The GPIO pads, when used as inputs, can be connected to a digital output of another
device and report its status, provided this device has interface levels compatible with
the 2.8V CMOS levels of the GPIO.
If the digital output of the device to be connected with the GPIO input pad has
interface levels different from the 2.8V CMOS, then it can be buffered with an open
collector transistor with a 47K pull up to 2.8V.
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