Mcu Interface - Quectel EC20 Circuit Diagrams

6
D
U201
1
VDD
2
GND
3
TXD
4
RXD
5
DTR
6
RI
7
CTS
8
RTS
9
DCD
10
USB_VBUS
11
USB_DP
12
USB_DM
13
USB_ID
14
GPIO_01
15
GPIO_02
C
16
GPIO_03
17
GPIO_04
18
GPIO_05
19
GPIO_06
20
GPIO_07
The necessary control circuit
It is used to turn on or off the module.
[2] ON/OFF_MCU
B
Notes:
1. U201 represents customer's MCU.
2. EC20 can only work as a USB device and support FS/HS mode. To communicate with USB interface,
MCU needs to support USB host or OTG function. The VBUS pins of MCU and EC20 need to be
provided by 5V power for USB detection, and VBUS_CONTROL turns on and off VBUS power supply.
3. AP_READY can be configured to high level detection and low level detection. For more details about AP_READY,
A
please refer to the document <Quectel_EC20_Hardware_Design> and <Quectel_EC20_AT_Commands_Manual>.
4. Transistor circuits (Q203~Q207) are used for level translation.
6
5
VDD_MCU
TXD_MCU [4]
[4]
RXD_MCU
[4]
DTR_MCU
[4]
RI_MCU
CTS_MCU [4]
Reserved
[4]
RTS_MCU
DCD_MCU [4]
[1,2,8]
USB_VBUS
R201 0R
C201
NM
R202 0R
R203 0R
[2]
VBUS_CONTROL
[2]
ON/OFF_MCU
[2]
RESET_MCU
[2]
W_DISABLE_M
[2]
SLEEP_STATUS
[7]
SD_PWR_EN
[3]
VBAT_EN
It is used to reset the module.
[1,8]
PWRKEY
Q205
Q204
[2] RESET_MCU
DTC043ZEBTL
DTC043ZEBTL
5
4 3

MCU Interface

5V power source from main board.
Q201
DC_5V
S
[1,8]
USB_DP
R204
10K
[1,8]
USB_DM
[2] VBUS_CONTROL
VBUS_CONTROL = High level, Q201 conducts.
VDD_EXT
[1]
RESET_N
[2] SLEEP_STATUS
AP_READY High level detection
3
4
2
SI2333CDS-T1
USB_VBUS [1,2,8]
D
[2] W_DISABLE_M
Q202
DTC043ZEBTL
VDD_MCU
R206
47K
[1,2]
AP_READY
[2] SLEEP_STATUS
Q206
DTC043ZEBTL
AP_READY Low level detection
Quectel Wireless Solutions
DRAWN BY
Mountain.ZHOU
CHECKED BY
Radom.XIANG
2
1
D
VDD_EXT
R205
10K
[1]
W_DISABLE#
Q203
DTC043ZEBTL
C
VDD_EXT
R208
R207 4.7K
10K
Q207
2SA2018
B
AP_READY [1,2]
R209
100K
PROJECT
TITLE
EC20 Reference Design
MCU Interface
SIZE VER
A2 1.0
SHEET 2 OF 8 DATE 2015/3/30
1
A