Problem with Quectel EG915U-EU usb connection

Post Reply
DiXmon
Posts: 3
Joined: Tue Oct 07, 2025 6:43 pm

Problem with Quectel EG915U-EU usb connection

Postby DiXmon » Mon Dec 08, 2025 9:18 am

Hi,
In my project, I am using an ESP32-S3 and a Quectel EG-915U-EU modem connected to the ESP32-S3 via D+ and D-. To work with the modem, I am using the iot_usbh_modem component. The problem is that the connection with the modem periodically drops.
The modem is powered from a separate power supply, and the ESP32-S3 is also powered separately. There don’t seem to be any power issues. Has anyone encountered this problem and can suggest a solution?

Code: Select all

 (23082624) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23082624) DISPLAY: WiFi display: ON (waiting for connection)
I (23082634) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
I (23085014) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23085014) WIFI: WiFi disconnected. Retrying...
I (23085014) DISPLAY: WiFi display: ON (waiting for connection)
I (23085024) DISPLAY: WIFI INTERNET: DOWN (red)
I (23085034) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23085034) DISPLAY: WiFi display: ON (waiting for connection)
I (23085044) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
W (23086044) ***MAIN***: ===================================================================================

I (23086064) ***MAIN***: GSM rssi=21, ber=99
I (23086064) ***MAIN***: ******** IP address of google.com: 142.251.36.78
I (23086074) ***MAIN***: Ping addr 8.8.8.8 Restart..
I (23086204) ***MAIN***: 64 bytes from 8.8.8.8 icmp_seq=1 ttl=114 time=128 ms

E (23086234) USBH_CDC: RX xfer failed, status 1
E (23086234) USBH_CDC: RX xfer failed, status 1
E (23086234) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086234) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086244) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086254) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086264) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086264) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086274) USB HOST: EP command error: ESP_ERR_INVALID_STATE
E (23086274) USB HOST: EP command error: ESP_ERR_INVALID_STATE
I (23086294) modem_board: Modem state STAGE_DTE_LOSS, Start
W (23086294) esp-modem: Waiting exit the PPP mode gracefully
I (23086294) modem_board: Modem state STAGE_DTE_LOSS, Success!
E (23086304) USBH_CDC: usbh_cdc_write_bytes(1005): Device is not connected
E (23086304) esp-tls-mbedtls: read error :-0x004C
E (23086314) transport_base: esp_tls_conn_read error, errno=Software caused connection abort
E (23086324) mqtt_client: esp_mqtt_handle_transport_read_error: transport_read() error: errno=113
E (23086334) MQTT_APP: MQTT error: 1
E (23086334) mqtt_client: mqtt_process_receive: mqtt_message_receive() returned -2
I (23086344) MQTT_APP: MQTT_EVENT_DISCONNECTED
I (23087424) WIFI: WiFi disconnected. Retrying...
I (23087424) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23087424) DISPLAY: WiFi display: ON (waiting for connection)
I (23087434) DISPLAY: WIFI INTERNET: DOWN (red)
I (23087454) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23087454) DISPLAY: WiFi display: ON (waiting for connection)
I (23087464) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
E (23087554) ENUM: LANGID 0x409 not found
Found IN endpoint: 138
Found OUT endpoint: 7
Found NOTIF endpoint: 137
I (23087554) USBH_CDC: Opened cdc device: 14
Found IN endpoint: 132
Found OUT endpoint: 2
Found NOTIF endpoint: 131
*** Device descriptor ***
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0x0
bDeviceSubClass 0x0
bDeviceProtocol 0x0
bMaxPacketSize0 64
idVendor 0x2c7c
idProduct 0x901
bcdDevice 3.10
iManufacturer 1
iProduct 2
iSerialNumber 3
bNumConfigurations 1
*** Configuration descriptor ***
bLength 9
bDescriptorType 2
wTotalLength 263
bNumInterfaces 9
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xe0
bMaxPower 400mA
*** Interface Association Descriptor ***
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 0x2
bFunctionSubClass 0x6
bFunctionProtocol 0x0
iFunction 4
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 0
	bAlternateSetting 0
	bNumEndpoints 1
	bInterfaceClass 0x2
	bInterfaceSubClass 0x6
	bInterfaceProtocol 0x0
	iInterface 6
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x81	EP 1 IN
		bmAttributes 0x3	INT
		wMaxPacketSize 16
		bInterval 32
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 1
	bAlternateSetting 0
	bNumEndpoints 0
	bInterfaceClass 0xa
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 1
	bAlternateSetting 1
	bNumEndpoints 2
	bInterfaceClass 0xa
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 5
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x82	EP 2 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x1	EP 1 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 2
	bAlternateSetting 0
	bNumEndpoints 3
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x84	EP 4 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x2	EP 2 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x83	EP 3 IN
		bmAttributes 0x3	INT
		wMaxPacketSize 64
		bInterval 32
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 3
	bAlternateSetting 0
	bNumEndpoints 2
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x85	EP 5 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x3	EP 3 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 4
	bAlternateSetting 0
	bNumEndpoints 2
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x86	EP 6 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x4	EP 4 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 5
	bAlternateSetting 0
	bNumEndpoints 2
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x87	EP 7 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x5	EP 5 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 6
	bAlternateSetting 0
	bNumEndpoints 2
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x88	EP 8 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x6	EP 6 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 7
	bAlternateSetting 0
	bNumEndpoints 3
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x8a	EP 10 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x7	EP 7 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x89	EP 9 IN
		bmAttributes 0x3	INT
		wMaxPacketSize 64
		bInterval 32
	*** Interface descriptor ***
	bLength 9
	bDescriptorType 4
	bInterfaceNumber 8
	bAlternateSetting 0
	bNumEndpoints 2
	bInterfaceClass 0xff
	bInterfaceSubClass 0x0
	bInterfaceProtocol 0x0
	iInterface 8
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x8b	EP 11 IN
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
		*** Endpoint descriptor ***
		bLength 7
		bDescriptorType 5
		bEndpointAddress 0x8	EP 8 OUT
		bmAttributes 0x2	BULK
		wMaxPacketSize 64
		bInterval 0
I (23088064) modem_board: DTE reconnect, reconnecting ...

I (23088064) USBH_CDC: Opened cdc device: 14
I (23088074) USBH_CDC: New device connected, address: 14
I (23088074) ***MAIN***: Task dump
I (23088084) ***MAIN***: Load	Stack left	Name	PRI
I (23088094) ***MAIN***: nan 	636	modem_daemon 6
I (23088094) ***MAIN***: nan 	9516	display_task 5
I (23088104) ***MAIN***: nan 	320	main 1
I (23088104) ***MAIN***: nan 	696	IDLE0 0
I (23088114) ***MAIN***: nan 	688	IDLE1 0
I (23088114) ***MAIN***: nan 	1992	tiT 18
I (23088124) ***MAIN***: nan 	408	mqtt_inet_evt 5
I (23088124) ***MAIN***: nan 	4124	system_events 5
I (23088134) ***MAIN***: nan 	1780	ping 2
I (23088134) ***MAIN***: nan 	888	mqtt_task 5
I (23088144) ***MAIN***: nan 	996	usb_data_recv 6
I (23088144) ***MAIN***: nan 	536	ipc0 24
I (23088154) ***MAIN***: nan 	1904	usb_lib 5
I (23088154) ***MAIN***: nan 	2968	esp_timer 22
I (23088164) ***MAIN***: nan 	1252	wifi 23
I (23088164) ***MAIN***: nan 	368	sys_evt 20
I (23088174) ***MAIN***: nan 	1620	usbh_cdc 5
I (23088174) ***MAIN***: nan 	1320	Tmr Svc 1
I (23088184) ***MAIN***: nan 	528	ipc1 24
I (23088184) ***MAIN***: Free heap=8498092 Free mini=8257536 bigst=8445756, internal=127064 bigst=77824
I (23089074) modem_board: reconnect after 2s...
I (23089824) WIFI: WiFi disconnected. Retrying...
I (23089834) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23089834) DISPLAY: WiFi display: ON (waiting for connection)
I (23089834) DISPLAY: WIFI INTERNET: DOWN (red)
I (23089854) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23089854) DISPLAY: WiFi display: ON (waiting for connection)
I (23089864) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
I (23090074) modem_board: reconnect after 1s...
I (23090074) modem_board: Modem state STAGE_SYNC, Start
I (23090214) modem_board: Network Auto reconnecting ...
I (23090214) modem_board: Modem state STAGE_SYNC, Success!
I (23090314) modem_board: Modem state STAGE_SET_URC, Start
I (23090414) modem_board: URC port set to "usbmodem" successfully
I (23090414) modem_board: Modem state STAGE_SET_URC, Success!
I (23090514) modem_board: Modem state STAGE_SET_APN_DEFAULT, Start
W (23090614) esp_modem_dce: esp_modem_dce_generic_command(31): Command:AT+CGDCONT=1,"IP",""
...failed
W (23090614) modem_board: Failed to send APN clear command
W (23090614) modem_board: Modem state STAGE_SET_APN_DEFAULT, Failed, retry1, after 3000ms...
I (23092234) WIFI: WiFi disconnected. Retrying...
I (23092244) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23092244) DISPLAY: WiFi display: ON (waiting for connection)
I (23092244) DISPLAY: WIFI INTERNET: DOWN (red)
I (23092264) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23092264) DISPLAY: WiFi display: ON (waiting for connection)
I (23092274) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
I (23092334) esp-netif_lwip-ppp: ppp: User interrupt
I (23092334) esp-modem-netif: PPP state changed event 5: (NETIF_PPP_ERRORUSER)
I (23093624) modem_board: Modem state STAGE_SET_APN_DEFAULT, Start
I (23093704) modem_board: APN cleared successfully
I (23093704) modem_board: Modem state STAGE_SET_APN_DEFAULT, Success!
I (23093804) modem_board: Modem state STAGE_CHECK_SIM, Start
I (23093904) modem_board: SIM Card Ready
I (23093904) modem_board: Modem state STAGE_CHECK_SIM, Success!
I (23094004) modem_board: Modem state STAGE_CHECK_SIGNAL, Start
I (23094644) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23094644) WIFI: WiFi disconnected. Retrying...
I (23094644) DISPLAY: WiFi display: ON (waiting for connection)
I (23094654) DISPLAY: WIFI INTERNET: DOWN (red)
I (23094664) DISPLAY: WiFi update: enabled=1, connected=0, rssi=-100, ssid='', internet_up=0
I (23094664) DISPLAY: WiFi display: ON (waiting for connection)
I (23094674) DISPLAY: WiFi EVENT: connected=0, rssi=-100, ssid=''
I (23096104) modem_board: Signal quality: rssi=21, ber=99
I (23096104) modem_board: Modem state STAGE_CHECK_SIGNAL, Success!
I (23096204) modem_board: Modem state STAGE_CHECK_REGIST, Start
Top
lichurbagan
Posts: 59
Joined: Thu Nov 13, 2025 3:20 pm

Re: Problem with Quectel EG915U-EU usb connection

Postby lichurbagan » Tue Dec 09, 2025 4:40 pm

Your modem drops because USB host traffic stalls. The ESP32-S3 USB host is sensitive. Small timing glitches break transfers. Power looks fine, but USB stability does not.

Add a common ground between both supplies. Keep D+ and D− under 10 cm. Use a shielded cable. Add 22 Ω series resistors on both data lines. Disable other heavy tasks during PPP. Increase the USB host task stack. Raise the CDC transfer timeout. Update to the **latest ESP-IDF** because USB host fixes are ongoing. If issues persist, add a **USB hub with its own PHY** between the ESP32-S3 and the modem.
Top
DiXmon
Posts: 3
Joined: Tue Oct 07, 2025 6:43 pm

Re: Problem with Quectel EG915U-EU usb connection

Postby DiXmon » Mon Dec 15, 2025 9:58 am

Thank you. The problem has been solved. I replaced the ESP32-C3 dev board, and the issue disappeared.
Top
Post Reply

Return to “General Discussion”

Who is online

Users browsing this forum: Applebot, Baidu [Spider], Bing [Bot], meta-externalagent and 9 guests