UMTS/HSPA Module Series
UC20 PPP Application Note
UC20_PPP_Application_Note Confidential / Released 9 / 29
3.2. Recommended Procedure for PPP Setup
Connect_Count
<5
Power On the
Module
AT+CPIN
？
Query SIM Card
Status
AT+CGREG?
Query PS
network
1. Set APN by AT+CGDCONT
2. Start PPP Dialing by ATD*99#
Return CONNECT
MCU got IP and
DNS
Data
Transmission
MCU sends
PPP
Terminate-
Request
packet
Connec+
Recommended Power ON/OFF:
1. Power OFF: Pull Power Key from
high to low, then cut off power after
12s.
2. Power ON: Pull Power Key to low
in 1s.
3. Pull Power Key back to high
when finishing Power OFF or
Power ON.
Exit from the PPP dialing if
SIM Card is not ready in 10s
SIM card is ready
Query SIM Card Status:
AT+CPIN/AT+QINISTAT. Reboot
module if module failed to detect
SIM card in 10s with AT+CPIN?.
PS Network
：
1. It indicates that module has
registered to PS when
AT+CGREG? returns 1 or 5.
2. It is able to go to next step
without registering to PS in 60s.
APN Configuration
：
1. APN must be set by
AT+CGDCONT
2. Use AT+CGACT? to check
whether current context has been
activated when AT+CGDCONT
returns error.
Y
Y
N
Packet Interaction
1. Exit from the procedure of Packet
Interaction by
“
+++
”
.
2. Module will report NO CARRIER
when PPP connection is
terminated.
LCP Negotiation
1. If UART is used, ensure the
baudrate between MCU and
module is the same.
AUTH Negotiation
1. Ensure the type of AUTH is one
of PAP(0xc023) and
CHAP(0xc223).
IPCP Negotiation
1. Check if MCU gets legal IP and
DNS address.
2. Check whether the amount of
DNS MCU is equal to the amount
requested by MCU.
3. Terminate PPP connection if
IPCP negotiation between TA and
TE is not completed in 90s, and
then retry PPP setup.
Exception Handling
1. Check whether the PPP
Terminate-Request packet is right.
2. Reboot module if the steps above
do not work.
Start timer when
IPCP negotiation
begins
Succeed to
negotiate IPCP
in 90s
Y
N
MCU receives
PPP Terminate-
Ack packet in 3s
Send Count<5
Exception Handling
Send Count++
LCP Negotiation
AUTH Negotiation
IPCP Negotiation
Packet Interaction
OK
OK
OK
N
Y
Y
N
N
1.Synchronization between TE and TA
2. Fix and save baudrate by AT+IPR=xxx&W, if
USB modem port is used, this coud be ignored
Network
：
1. It indicates that module has
registered to network when
AT+CREG? returns 1 or 5.
2. Reboot the module if it failed to
register to network in 60s.
Exit from the PPP dialing
if module failed to register
to network in 60s
AT+CREG
？
Query network
Register to network in 60s
Figure 3: Flowchart for PPP Setup
Quectel
Confidential
