User's Manual

4. Digital I/O Connection
If the voltage level of peripheral interface circuit does not match module interface, the power
consumption of the system could increase, and could even cause the module damaged.
 Each digital I/O of the module operates in a 2.8V logic level inside the module. The voltage
level of those digital interfaces connected to the module should match the electrical
characteristics of the module listed in Table 2. Otherwise, a level shifter circuit must be
inserted between the host and the module.
Table 1: Digital I/O electrical characteristics
SYMBOL
MIN
MAX
UNITS
VIL
0
0.67
V
VIH
1.7
3.1
V
VOL
0
0.34
V
VOH
2.0
2.8
V
 For direct connection between I/Os, please pay attention to I/Os’ input or output configuration.
If the I/O direction configuration conflicts with each other, the power consumption could
increase, and the module could be very hot, and even be damaged. For example, it is forbidden
that user’s I/O outputs a low level while module’s connected I/O outputs a high level.