User's Manual

MeiG hardware design guide
8
Figure 4.8： Reset using the key circuit
Figure 4.9：Reset Module Using External Signa
When the pin is high, the voltage is typically 1.8V. Therefore, for users with a level of 3V or 3.3V,
it is not possible to directly use the GPIO of the MCU to drive the pin. An isolation circuit is required.
The hardware parameters of the RESET can refer to the following table:
Table 4.1: RESET Hardware Parameters
Pin
Description
Minimum
Typical
Maximum
Unit
RESET
Input high level
1
-
-
V
Input low level
-
-
0.65
V
Pull down
effective time
500
-
ms
Figure 4.7: Using PWRKEY boot timing diagram
4.3 VCOIN Power
When VBAT is disconnected, the user needs to save the real-time clock. The VCOIN pin cannot be
suspended. It should be connected to a large capacitor or battery. When external capacitor is connected,
the recommended value is 100uF, and the real-time clock can be kept for 1 minute. The reference
design circuit is used when the RTC power supply uses an external large capacitor or battery to power
the RTC inside the module: