User's Manual

HF-A21-SMT Embedded WiFi Module User Manual
Shanghai High-Flying Electronics Technology Co., Ltd
www.hi-flying.com
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There is 22K&4.7uF reset circuit. When module power up or some issue happened, MCU need
assert nRST signal “0” at least 300ms, then set” 1” to keep module fully reset.
nReady- Module boot up ready signal. Output. Logics “0” effective.
The module will output “0” “or “Palmodic Signal” after normal boot up. This signal used to judge if
module finish boot up and ready for application or working at normal mode.
nLink- Module WIFI connection indication. Output.
When module connect to AP (STA mode) or some WiFi STA connect to module (AP mode), the
module will output “0”. This signal used to judge if module already at WiFi connection status.
nReload- Module restore to factory default configuration.Input. Logics “0” effective.
User can assert nReload signal “0” more than 3‟s through button or MCU pin, then release,
module will restore to factory default configuration and re-start boot up process.
UART_TXD/RXD- UART port data transmit and receive signal.
1.3.2. 10/100M Ethernet Interface
HF-A21-SMT modules provide one 10/100M Ethernet PHY layer interface for data transition or
user configuration. This Ethernet support with transformer and without transformer (PHY-to-PHY)
2 kinds of connection.
1.3.2.1. Ethernet Connection with Transformer
User board put Ethernet transformer and RJ-45 connector. This is a general 10/100M Ethernet
phy layer connection. The reference design as following:
Figure 9. Ethernet Reference Design with Transformer
1.3.2.2. Ethernet Connection without Transformer
For this application, Ethernet will work as internal data transmition interface and save one
transformer and RJ-45 connector. Ethernet PHY-to-PHY connection will use AC coupled
connection. This is a space and cost optimized solution. Hardware reference design as following:
Note: VCC signal at reference design shall base on user board PHY chipset voltage level, such
as 2.5V power supply for general Ethernet PHY chipset.