Active1 year, 3 months ago
I use GSM module Telit GL865 in UART communication with STM32F7 MCU and softwares STM32CubeMX, Keil.
Ppp Over Serial
Using PPP over ATM (PPPoA) 27.1. FreeBSD supports the Point-to-Point (PPP) protocol which can be used to establish a network or Internet connection using a dial-up modem. This chapter describes how to configure modem-based communication services in FreeBSD. Setting Up the Serial Console.
When I send AT commands over UART to GSM module as below, I get an IP address by the internal stack of the GSM module and ping it successfully:
However, when I start a PPPoS session, I cannot ping the IP which was successfully established over PPP.
The IP, gateway and netmask addresses that are established over PPP stack are as follows:
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The first problematic thing I viewed is the Netmask address; however, LwIP PPPoS establishes this.
Secondly, after the establishment above, MCU and GSM module starts to send periodic data to each other as
'~y '
with length 49 and 53 respectively.That means my debugging of
printf( )
cannot show me all of the periodic data.Thirdly, the most important, when I ping the IP of GSM above, the periodic data
'~y '
with length 68, is sent much more in time between MCU and GSM, means that pinging triggers the communication between GSM and MCU but no response back.I use interrupt based UART transceiving which starts to fill the received buffer and put it into
pppos_input_tcpip(ppp, recBuffer, recIndex)
unless new data comes in 10ms.The main thread, and the timer interrupt is as follows:
Systick Handler that checks the RX buffer and sets the send flag to send the data to ppp if data stops coming after 10ms:
Data communication between GSM and STM32 seems OK to me(!) and triggered with ping request; however, no ping response.
In my opinion, problem may be about the connection between
ppp_netif
and ppp_netif(ppp)
, netmask or ping implementation of the LwIP stack..Sarp Engin Daltaban
Sarp Engin DaltabanSarp Engin Daltaban
1 Answer
The answer is activating outgoing and incoming ICMP checksum options of STM32CubeMX..So, activating LWIP_ICMP module is insufficient by itself to response ping requests.
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