# AT+SQNHTTPRCV: Systematic byte mutation during binary download over HTTPS
**URL:** https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582
**Category:** LTE-M / NB-IoT (Monarch)
**Created:** [September 3, 2026, 1:16am UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582 "2026-09-03T01:16:20Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Ben-AgFlo](https://forum.sequans.com/u/Ben-AgFlo)
#### Post date: [September 3, 2026, 1:16am UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582/1 "2026-09-03T01:16:20Z")
Hello
We are trying to download a binary file onto a custom host MCU platform connected via UART to a GM02S running UE8.2.0.2. File is hosted on Azure Blob Storage and we want to download over HTTPS using the modem’s built-in HTTP stack (`AT+SQNHTTPCFG`, `AT+SQNHTTPCONNECT`, `AT+SQNHTTPQRY`, and `AT+SQNHTTPRCV`).
When downloading raw binary chunks via `AT+SQNHTTPRCV=2,1500`, the incoming byte stream undergoes a deterministic bitwise mutation where **Bit 2 (`0x04`) is forcefully set on specific low-value bytes**.
Specifically:
- `0x01` (`0000 0001`) consistently arrives as `0x05` (`0000 0101`).
- `0x02` (`0000 0010`) consistently arrives as `0x06` (`0000 0110`).
- `0x03` (`0000 0011`) consistently arrives as `0x07` (`0000 0111`).
There might be others but I think this illustrate sufficiently the issue. This is **not random noise** or dropped bytes—the byte alignment and total file length match the source image exactly, but every instance of `0x01` across the entire payload is translated to `0x05` when compared against the original `.bin` file in GHex.
What we tried so far:
- Verified `AT+IFC?` returns `+IFC: 2,2` (Hardware RTS/CTS flow control active). This never gave us any issue.
- Explicitly switched `AT+CSCS="HEX"` prior to issuing `AT+SQNHTTPRCV`.
- Queried `AT+ICF?` returns `+ICF: 3`, this never gave use any issue.
Questions are as follows:
1. Does `AT+SQNHTTPRCV` apply any internal escape sequences, control-character mapping, or internal buffer translations to low-value ASCII bytes (`0x01`–`0x03`) when streaming raw octet streams (`application/octet-stream`)?
2. Is there a recommended AT command configuration or character set selection specifically required to guarantee transparent 8-bit binary pass-through when reading HTTP responses via UART?
3. Are there any known driver or firmware quirks in release LR8.2 regarding UART output serialization during `AT+SQNHTTPRCV`?
Any guidance on achieving transparent 8-bit binary streaming via `AT+SQNHTTPRCV` would be greatly appreciated.
Thank you.
---
### Author:  [@Eros](https://forum.sequans.com/u/Eros)
#### Post date: [September 3, 2026, 12:58pm UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582/2 "2026-09-03T12:58:11Z")
Hi Ben-AgFlo:
Could you provide me the binary file and the AT commands you used for HTTPS test?
Could you run ATI1 to get the exact sw version? Is it LR8.2.0.2-59200?
Best regards,
Eros
---
### Author:  [@Ben-AgFlo](https://forum.sequans.com/u/Ben-AgFlo)
#### Post date: [September 4, 2026, 12:29am UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582/3 "2026-09-04T00:29:32Z")
> [@Eros](#):
>
> Could you provide me the binary file and the AT commands you used for HTTPS test?
Here is the set of commands used to fetch binary file
`AT+CSCS="HEX"`
`AT+IFC=2,2`
`AT+SQNHTTPDISCONNECT=2`
`AT+SQNHTTPCFG=2`
`AT+SQNSPCFG=1,2,"",1`
`AT+SQNHTTPCFG=2,"``xyz.blob.core.windows.net``",443,0,"","",1,60,1,1`
`AT+SQNHTTPCONNECT=2`
! Wait for URC: `+SQNHTTPCONNECT: 2,0`
`AT+SQNHTTPQRY=2,0,"/device_firmwares/5.7.0/ultrasound/5.7.0.bin?"`
! Wait for URC: `+SQNHTTPRING: 2,200,"application/octet-stream",204800`
`AT+SQNHTTPRCV=2,1500`
ATI1 command output:
`ATI1`
`UE8.2.0.2`
`LR8.2.0.2-59200`
I will not paste our firmware file of our product here. I will send privately a truncated part of it that does not contain any sensitive information.
---
### Author:  [@Eros](https://forum.sequans.com/u/Eros)
#### Post date: [September 6, 2026, 8:32am UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582/4 "2026-09-06T08:32:33Z")
Thank you, **[Ben-AgFlo](https://forum.sequans.com/u/ben-agflo)**
It’s enough, I will use it for issue reproducing.
Best regards,
Eros
---
### Author:  [@Eros](https://forum.sequans.com/u/Eros)
#### Post date: [September 21, 2026, 3:31am UTC](https://forum.sequans.com/t/at-sqnhttprcv-systematic-byte-mutation-during-binary-download-over-https/582/5 "2026-09-21T03:31:24Z")
Hi **[Ben-AgFlo](https://forum.sequans.com/u/ben-agflo):**
Didn’t reproduce the issue, could you try to use PC ( instead of MCU) and check if same issue?
you can use UARt1 or UART0 to connect to PC using RS232-USB cable ( like FTDI RS232-USB cable ).
Best regards,
Eros