User's Manual

LTE Module Series
EC21 Hardware Design
EC21_Hardware_Design Confidential / Released 55 / 94
BT_CTS* 40 DO BT UART clear to send 1.8V power domain
PCM_IN
1)
24 DI PCM data input 1.8V power domain
PCM_OUT
1)
25 DO PCM data output 1.8V power domain
PCM_SYNC
1)
26 IO PCM data frame sync signal 1.8V power domain
PCM_CLK
1)
27 IO PCM data bit clock 1.8V power domain
BT_EN* 139 DO
WLAN function control via FC20
module. Active high.
1.8V power domain
1. “*” means under development.
2.
1)
Pads 24~27 are multiplexing pins used for audio design on EC21 module and BT function on FC20
module.
The following figure shows a reference design of wireless connectivity interfaces with Quectel FC20
module.
Figure 29: Reference Circuit of Wireless Connectivity Interfaces with FC20 Module
NOTES