Espressif Systems ESP8684 Series, Руководство по проектированию аппаратного обеспечения, Страница: 12 / 28

2 Schematic Checklist
Table 2: Strapping Pins
Booting Mode
1
Pin Default SPI Boot Download Boot
GPIO8 N/A Don’t care 1
GPIO9
Internal weak
pull-up
1 0
Enabling/Disabling ROM Messages Print During Booting
Pin Default Functionality
GPIO8 N/A
When the value of eFuse field EFUSE_UART_PRINT_CONTROL is
0 (default), print is enabled and not controlled by GPIO8.
1, if GPIO8 is 0, print is enabled; if GPIO8 is 1, it is disabled.
2, if GPIO8 is 0, print is disabled; if GPIO8 is 1, it is enabled.
3, print is disabled and not controlled by GPIO8.
1
The strapping combination of GPIO8 = 0 and GPIO9 = 0 is invalid and will trigger unexpected be-
havior.
Figure 8 shows the setup and hold times for the strapping pins before and after the CHIP_EN signal goes high.
Details about the parameters are listed in Table 3 .
CHIP_EN
t1 t0
Strapping pin
V
IL_nRST
V
IH
Figure 8: Setup and Hold Times for the Strapping Pins
Table 3: Parameter Descriptions of Setup and Hold Times for the Strapping Pins
Min
Parameter Description (ms)
t
0
Setup time before CHIP_EN goes from low to high 0
t
1
Hold time after CHIP_EN goes high 3
2.9 GPIO
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ESP8684 Series Hardware Design Guidelines v1.1