esp-modem: Missing end SOF issue

[swaroopsuthar]

I have implemented this example. and UART connection was working but an issue exists when I call any esp_http. that time Rx butter reading get stuck.

UART Rx buffer gets to start with f9 and end with f9. but sometimes the pattern was broken.

I (00:00:24.072) esp-netif_lwip-ppp: Connected
I (00:00:24.077) esp-netif_lwip-ppp: Name Server1: 117.96.122.42
I (00:00:24.083) esp-netif_lwip-ppp: Name Server2: 59.144.144.99
I (00:00:24.090) server_comm: Modem Connect to PPP Server
I (00:00:24.096) server_comm: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I (00:00:24.105) server_comm: IP          : 10.175.192.118
I (00:00:24.111) server_comm: Netmask     : 255.255.255.255
I (00:00:24.117) server_comm: Gateway     : 10.64.64.64
I (00:00:24.123) server_comm: Name Server1: 117.96.122.42
I (00:00:24.129) server_comm: Name Server2: 59.144.144.99
I (00:00:24.135) server_comm: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I (00:00:24.144) server_comm: GOT ip event!!!
local  IP address 10.175.192.118
remote IP address 10.64.64.64
primary   DNS address 117.96.122.42
secondary DNS address 59.144.144.99
ppp phase changed[1]: phase=10
I (00:00:24.164) server_comm: [APP] Free memory: 63364 bytes
received < f9 09 ef 0f 41 54 2b 43 53 51 0d 3b f9 f9 09 ef 1f 0d 0a 2b 43 53 51 3a 20 32 33 2c 39 39 0d 0a 27 f9 f9 09 ef 0d 0d 0a 4f 4b 0d 0a d8 f9
I (00:00:24.212) esp-modem: Copy 33 from next frame to beginning of the buffer
I (00:00:24.220) esp-modem: Copy 12 from next frame to beginning of the buffer
I (00:00:24.269) server_comm: rssi: 23, ber: 99
W (00:00:24.269) server_comm: FOTA Version http://jsonplaceholder.typicode.com/todos/1
pppos_netif_output[1]: proto=0x21, len = 44
received < f9 05 ef 63 7e 21 45 00 00 2c 00 00 40 00 33 06 1e ec ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f2 b7 27 4f 86 60 12 72 10 de 27 00 00 02 04 05 14 92 2d 7e fd f9
pppos_input[1]: got 49 bytes
ppp_input[1]: ip in pbuf len=44
pppos_netif_output[1]: proto=0x21, len = 40
pppos_netif_output[1]: proto=0x21, len = 161
received < f9 05 ef 5b 7e 21 45 00 00 28 95 47 40 00 33 06 89 a8 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 10 72 10 f4 cb 00 00 08 e9 7e d7 f9 f9 05 ef 68 02 7e 21 45 00 01 2e 95 48 40 00 33 06 88 a1 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 18 72 10 bc e3 00 00 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d 0a 44 61 74 65 3a
pppos_input[1]: got 45 bytes
ppp_input[1]: ip in pbuf len=40
I (00:00:24.677) esp-modem: Copy 69 from next frame to beginning of the buffer
W (00:00:24.684) esp-modem: Missing end SOF
received < f9 05 ef 68 02 7e 21 45 00 01 2e 95 48 40 00 33 06 88 a1 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 18 72 10 bc e3 00 00 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d 0a 44 61 74 65 3a 20 57 65 64 2c 20 32 31 20 4a 75 6e 20 32 30 32 33 20 31 33 3a 31 35 3a 30 30 20 47 4d 54 0d 0a 53 65 72 76 65 72 3a 20 41 70 61 63 68 65 2f 32 2e 34 2e 31 38 20 28 55 62 75 6e 74 75 29 0d 0a 4c 61 73 74 2d 4d 6f 64 69 66 69 65 64 3a 20 54 68 75 2c 20 30 39 20 46 65 62 20 32 30 32 33 20 30 35 3a 31 34 3a 31 37 20 47 4d 54 0d 0a 45 54 61 67 3a 20 22 31 63 2d 35 66 34 33 64 37 33 64 66 61 61 66 63 22 0d 0a 41 63 63 65 70 74 2d 52 61 6e 67 65 73 3a 20 62 79 74 65 73 0d 0a 43 6f 6e 74 65 6e 74 2d 4c 65 6e 67 74 68 3a 20 32 38 0d
W (00:00:24.794) esp-modem: Missing end SOF
received <
W (00:00:24.839) esp-modem: Missing end SOF
received <
W (00:00:24.889) esp-modem: Missing end SOF
received < f9 05 ef 68 02 7e 21 45 00 01 2e 95 48 40 00 33 06 88 a1 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 18 72 10 bc e3 00 00 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d 0a 44 61 74 65 3a 20 57 65 64 2c 20 32 31 20 4a 75 6e 20 32 30 32 33 20 31 33 3a 31 35 3a 30 30 20 47 4d 54 0d 0a 53 65 72 76 65 72 3a 20 41 70 61 63 68 65 2f 32 2e 34 2e
W (00:00:25.263) esp-modem: Missing end SOF
received < f9 05 ef 68 02 7e 21 45 00 01 2e 95 48 40 00 33 06 88 a1 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 18 72 10 bc e3 00 00 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d 0a 44 61 74 65 3a 20 57 65 64 2c 20 32 31 20 4a 75 6e 20 32 30 32 33 20 31 33 3a 31 35 3a 30 30 20 47 4d 54 0d 0a 53 65 72 76 65 72 3a 20 41 70 61 63 68 65 2f 32 2e 34 2e 31 38 20 28 55 62 75 6e 74 75 29 0d 0a 4c 61 73 74 2d 4d 6f 64 69 66 69 65 64 3a 20 54 68 75 2c 20 30 39 20 46 65 62 20 32 30 32 33 20 30 35 3a 31 34 3a 31 37 20 47 4d 54 0d 0a 45 54 61 67 3a 20 22 31 63 2d 35 66 34 33 64 37
W (00:00:25.350) esp-modem: Missing end SOF
received <
W (00:00:25.399) esp-modem: Missing end SOF
received < f9 05 ef 68 02 7e 21 45 00 01 2e 95 48 40 00 33 06 88 a1 ce bd 8e fd 0a af c0 76 00 50 cb 9c 0d 11 3f f3 b7 27 4f ff 50 18 72 10 bc e3 00 00 48 54 54 50 2f 31 2e 31 20 32 30 30 20 4f 4b 0d 0a 44 61 74 65 3a 20 57 65 64 2c 20 32 31 20 4a 75 6e 20 32 30 32 33 20 31 33 3a 31 35 3a 30 30 20 47 4d 54 0d 0a 53 65 72 76 65 72 3a 20 41 70 61 63 68 65 2f 32 2e 34 2e
W (00:00:26.465) esp-modem: Missing end SOF