No, it wasn't working at the time I shipped the M308, but it doesn't work from the beginning even though it doesn't give an error.
I run several times M308 in version 3.4.5:

I run several times M308 in version 3.5.beta2:

In the old version it does change the reading, in the new one it doesn't. The values ​​displayed by the M308 and those displayed on the web server are exactly the same.
Yes, everything runs on the same board and same hardware, nothing has been changed except the firmware and the web server. I have tried other versions of web server with firmware 3.5beta2 and it still does not work, so it can be deduced that it is from the firmware of the board.
Yes, it's not SPI communication, but it's similar and it's connected to the same port.

No, it wasn't working at the time I shipped the M308, but it doesn't work from the beginning even though it doesn't give an error.
I run several times M308 in version 3.4.5:

I run several times M308 in version 3.5.beta2:

In the old version it does change the reading, in the new one it doesn't. The values ​​displayed by the M308 and those displayed on the web server are exactly the same.
Yes, everything runs on the same board and same hardware, nothing has been changed except the firmware and the web server. I have tried other versions of web server with firmware 3.5beta2 and it still does not work, so it can be deduced that it is from the firmware of the board.
Yes, it's not SPI communication, but it's similar and it's connected to the same port.

Thanks for your attention

This is the information that the board gives when putting the M308 S10.

I have also tried DHT21 with the same results.
I cannot use the bme280, since the machine is not prepared for this purpose (wiring issue).

I have been doing some more testing, the external SD card works fine (it was a problem with my configuration), but the DHT22 sensors do not work, when the machine starts up it seems to read the first value and then it never updates the value again, it just freezes.
I have tried those two models of DHT22

In version 3.4.5 only Aosong model (red) works, Asair model (blue) works for a while and then "Fault" error pops up. In version 3.5beta2 none works directly.
By the way, the Aosong models are practically impossible to get, now there is only Asair and they don't work well in any version.

When switch 1 (parking) is 0 there is no tool, if it is 1 the tool is in the parking lot.
When switch 2 (tool) is 1 the tool is in the carriage and if it is 0 the tool is not in the carriage. seeing the echos that are set to monitor those switches, before finishing leaving the tool, and after leaving it.
The results obtained seem to indicate that when sending a T1, Tpre and Tpost are executed twice, when leaving the tool (T-1) we have two cases:

• Without the delay (G4 P500) it executes Tfree and Tpost twice, it never enters the last conditional and the echo indicate so

• With the delay (G4 P500), it only executes Tfree and Tpost once and manages to enter the last conditional, also the status of the switches that the echo show us confirms the above.

Thanks in advance and if you need any more information let me know

The SPI communication does not work, I have installed two DHT22 sensors and an external SD to read print files and nothing works. This works perfectly in older versions.

M122:
=== Diagnostics ===
RepRapFirmware for Duet 3 MB6HC version 3.5beta2 (2022-12-23 18:27:08) running on Duet 3 MB6HC v1.01 (standalone mode)
Board ID: 0JD2M-999AL-D2PS0-6J9D8-3S46N-9NKV1
Used output buffers: 1 of 40 (38 max)
=== RTOS ===
Static ram: 151524
Dynamic ram: 109880 of which 0 recycled
Never used RAM 86268, free system stack 146 words
Tasks: NETWORK(ready,445.5%,209) ETHERNET(notifyWait,2.6%,401) HEAT(notifyWait,0.3%,307) Move(notifyWait,0.0%,258) CanReceiv(notifyWait,0.9%,773) CanSender(notifyWait,0.0%,335) CanClock(delaying,0.1%,340) TMC(notifyWait,107.9%,90) MAIN(running,172.0%,953) IDLE(ready,2.0%,30), total 731.4%
Owned mutexes:
=== Platform ===
Last reset 03:26:00 ago, cause: software
Last software reset at 2023-03-22 09:50, reason: User, GCodes spinning, available RAM 86228, slot 2
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0044a000 BFAR 0x00000000 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
Aux0 errors 0,11,0
Step timer max interval 236
MCU temperature: min 35.6, current 40.0, max 40.1
Supply voltage: min 23.8, current 23.8, max 23.9, under voltage events: 0, over voltage events: 0, power good: yes
12V rail voltage: min 12.0, current 12.0, max 12.1, under voltage events: 0
Heap OK, handles allocated/used 99/47, heap memory allocated/used/recyclable 2048/564/120, gc cycles 33
Events: 2 queued, 2 completed
Driver 0: standstill, SG min 0, mspos 40, reads 22871, writes 35 timeouts 0
Driver 1: standstill, SG min 0, mspos 904, reads 22876, writes 35 timeouts 0
Driver 2: standstill, SG min 0, mspos 200, reads 22888, writes 23 timeouts 0
Driver 3: standstill, SG min n/a, mspos 360, reads 22894, writes 17 timeouts 0
Driver 4: standstill, SG min n/a, mspos 8, reads 22901, writes 11 timeouts 0
Driver 5: standstill, SG min n/a, mspos 8, reads 22901, writes 11 timeouts 0
Date/time: 2023-03-22 13:16:10
Slowest loop: 10.27ms; fastest: 0.05ms
=== Storage ===
Free file entries: 9
SD card 0 detected, interface speed: 25.0MBytes/sec
SD card longest read time 0.6ms, write time 3.5ms, max retries 0
=== Move ===
DMs created 125, segments created 6, maxWait 7791519ms, bed compensation in use: none, comp offset 0.000
no step interrupt scheduled
=== DDARing 0 ===
Scheduled moves 77, completed 77, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 1], CDDA state -1
=== DDARing 1 ===
Scheduled moves 0, completed 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1, chamber heaters 5 10 12 -1, ordering errs 0
Heater 2 is on, I-accum = 0.0
Heater 5 is on, I-accum = 0.0
=== GCodes ===
Movement locks held by null, null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
SBC is idle in state(s) 0
Daemon is idle in state(s) 0
Aux2 is idle in state(s) 0
Autopause is idle in state(s) 0
File2 is idle in state(s) 0
Queue2 is idle in state(s) 0
Q0 segments left 0, axes/extruders owned 0x0800003
Code queue 0 is empty
Q1 segments left 0, axes/extruders owned 0x0000000
Code queue 1 is empty
=== CAN ===
Messages queued 111199, received 739955, lost 0, boc 0
Longest wait 3ms for reply type 6053, peak Tx sync delay 278, free buffers 50 (min 49), ts 61801/61800/0
Tx timeouts 0,0,0,0,0,0
=== Network ===
Slowest loop: 30.86ms; fastest: 0.03ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
HTTP sessions: 2 of 8
= Ethernet =
State: active
Error counts: 0 0 0 0 0 0
Socket states: 5 2 2 2 2 0 0 0
=== Multicast handler ===
Responder is inactive, messages received 0, responses 0

Firmware: 3.5beta2
Web server: 3.5beta1
Board: 6HC (standalone mode)
Core XY

The tests:
Switch 1 = Parking switch
Switch 2 = Tool switch

-With G4 P500:

-Without G4 P500:

Hi Tony, thank you for your answer. What I do is make a call to my own Gcode (G43) in the Tfree file that leads me to what you see in the image of the previous message. I do it this way because I have implemented a system to leave the tool when the printer starts up in case of having the tool in the carriage, therefore I only need to have two switches configured to leave the tool.
In the file that you see (G43) I verify that the tool sensor exists so that it does not give me an error, then I equalize a variable with the current time of the machine, this is for safety, if leaving the tool takes longer than the time I specify below stops and does not continue. Then I go to some first coordinates that only bring the tool closer to its parking place, I do the final part of the route in the "While true" adding to the variable sum 0.1 each time the loop is executed and moving the X axis to the coordinate which the sum variable tells me until the parking switch is 1. This makes the last two millimeters of travel smooth and controlled. When the parking sensor is 1, I deactivate the tool clamping (M42 P0) and move the carriage to a safe coordinate.
The G50 file is its own Gcode that pauses if it's printing and an "abort" if it's not printing.

Hello everyone,
My printer is a multitool so it takes a few seconds to pick up or put down a tool. When updating the board to the latest version of the firmware, when executing a T-1 with a picked up tool, it enters a loop in which it leaves the tool and then picks it up again. The solution I have found is to put a "G4 P500" in the "Tfree" files, but that problem did not exist in version 3.4.

Firmware: 3.5beta2
Web server: 3.5beta1
Board: 6HC (standalone mode)
Core XY