Figure 29: Reference Circuit Of Wireless Connectivity Interfaces With Fc20 Module - Quectel EC21 Series Hardware Design

BT_CTS* 40
1)
PCM_IN 24
1)
PCM_OUT 25
1)
PCM_SYNC 26
1)
PCM_CLK 27
BT_EN* 139
NOTES
1. "*" means under development.
1)
2. 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.
WLAN
COEX & Control

Figure 29: Reference Circuit of Wireless Connectivity Interfaces with FC20 Module

EC21_Hardware_Design
DO BT UART clear to send
DI PCM data input
DO PCM data output
IO PCM data frame sync signal
IO PCM data bit clock
WLAN function control via FC20
DO
module. Active high.
Module
SDC1_DATA3
SDC1_DATA2
SDC1_DATA1
SDC1_DATA0
SDC1_CLK
SDC1_CMD
WLAN_EN
WLAN_SLP_CLK
WAKE_ON_WIRELESS
COEX_UART_RX
COEX_UART_TX
PM_ENABLE
BT_EN
BT_RTS
BT_CTS
BT_TXD
BT BT_RXD
PCM_IN
PCM_OUT
PCM_CLK
PCM_SYNC
DCDC/LDO
Confidential / Released
LTE Module Series
EC21 Hardware Design
1.8V power domain
1.8V power domain
1.8V power domain
1.8V power domain
1.8V power domain
1.8V power domain
FC20 Module
SDIO_D3
SDIO_D2
SDIO_D1
SDIO_D0
SDIO_CLK
SDIO_CMD
WLAN_EN
32KHz_IN
WAKE_ON_WIRELESS
LTE_UART_TXD
LTE_UART_RXD
VDD_3V3
BT_EN
BT_UART_RTS
BT_UART_CTS
BT_UART_RXD
BT_UART_TXD
PCM_OUT
PCM_IN
PCM_CLK
PCM_SYNC
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