Magnetometer examples broken

[droogmic]

All 3 mag3110 examples appear to block before being able to get and print data.

#0  0x00004180 in <nrf51_hal::i2c::I2c<nrf51::TWI1>>::send_byte (self=0x20003e9c, byte=0x20003d7c "\020\000")
    at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/nrf51-hal-0.5.1/src/i2c.rs:88
#1  0x00004ae2 in <nrf51_hal::i2c::I2c<nrf51::TWI1> as embedded_hal::blocking::i2c::Write>::write (self=0x20003e9c, addr=14, bytes=...)
    at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/nrf51-hal-0.5.1/src/i2c.rs:213
#2  0x0000091a in <mag3110::Mag3110<I2C>>::write_register (self=0x20003e9c, reg=mag3110::CTRL_REG1, byte=0)
    at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/mag3110-0.1.3/src/lib.rs:154
#3  0x000007ac in <mag3110::Mag3110<I2C>>::stop_sampling (self=0x20003e9c) at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/mag3110-0.1.3/src/lib.rs:140
#4  0x00000946 in <mag3110::Mag3110<I2C>>::set_sampling_mode (self=0x20003e9c, dr=mag3110::HZ80, ov=mag3110::OV16)
    at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/mag3110-0.1.3/src/lib.rs:110
#5  0x00000bda in <mag3110::Mag3110<I2C>>::new (i2c=...) at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/mag3110-0.1.3/src/lib.rs:103
#6  0x00001706 in i2c_haldriver_printmagserial::main::{{closure}} (cs=0x20003fcc) at examples/i2c_haldriver_printmagserial.rs:80
#7  0x0000285c in cortex_m::interrupt::free (f=...) at /home/droogmic/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-0.5.2/src/interrupt.rs:69
#8  0x00001242 in i2c_haldriver_printmagserial::main () at examples/i2c_haldriver_printmagserial.rs:47

[therealprof]

Can't confirm. They all work "fine"(*) for me.

(*) The only one that kind of makes sense is the: i2c_hal_printmagserial, the i2c_haldriver_printmagserial waits for an interrupt which never occurs while i2c_direct_printmagserialdelivers exactly one (wonky) result.

[droogmic]

Interesting, I wonder what is different.

[droogmic]

FYI, still occurring, still not sure why:

cargo run --example i2c_hal_printmagserial
    Finished dev [unoptimized + debuginfo] target(s) in 0.04s                                                                                                                
     Running `arm-none-eabi-gdb target/thumbv6m-none-eabi/debug/examples/i2c_hal_printmagserial`
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Reading symbols from target/thumbv6m-none-eabi/debug/examples/i2c_hal_printmagserial...done.
Reset () at /home/xxx/.cargo/registry/src/github.com-1ecc6299db9ec823/cortex-m-rt-0.6.4/src/lib.rs:494
494     __pre_init();
semihosting is enabled
Loading section .vector_table, size 0xa8 lma 0x0
Loading section .text, size 0x6c20 lma 0xa8
Loading section .rodata, size 0x844 lma 0x6cd0
Start address 0x5ca4, load size 29964
Transfer rate: 9 KB/sec, 7491 bytes/write.
(gdb) break i2c_hal_printmagserial.rs:30
Breakpoint 1 at 0x4c8: file examples/i2c_hal_printmagserial.rs, line 30.
(gdb) continue
Continuing.
Note: automatically using hardware breakpoints for read-only addresses.

Breakpoint 1, main () at examples/i2c_hal_printmagserial.rs:30
30      if let Some(p) = microbit::Peripherals::take() {
(gdb) next
31          p.CLOCK.tasks_lfclkstart.write(|w| unsafe { w.bits(1) });
(gdb) 
32          while p.CLOCK.events_lfclkstarted.read().bits() == 0 {}
(gdb) 
32          while p.CLOCK.events_lfclkstarted.read().bits() == 0 {}
(gdb) 
33          p.CLOCK.events_lfclkstarted.write(|w| unsafe { w.bits(0) });
(gdb) 
33          p.CLOCK.events_lfclkstarted.write(|w| unsafe { w.bits(0) });
(gdb) 
35          p.RTC0.prescaler.write(|w| unsafe { w.bits(4095) });
(gdb) 
36          p.RTC0.evtenset.write(|w| w.tick().set_bit());
(gdb) 
37          p.RTC0.intenset.write(|w| w.tick().set_bit());
(gdb) 
38          p.RTC0.tasks_start.write(|w| unsafe { w.bits(1) });
(gdb) 
40          cortex_m::interrupt::free(move |cs| {
(gdb)

# Blocks here

[therealprof]

Guess we'll need to revisit then to make it more reliable.

[bodagovsky]

I have the same problem. First time I ran i2c_hal_printmagserial got only Welcome to the magnetometer reader! Then I tried to play with I2C addresses, and I started to get some values, but all of them were the same and never changed despite of moving the board for example, if i change this let _ = i2c.write(0x19, &[0x33, 0x32]); // let _ = i2c.write(0xE, &[0x11, 0x7f]); and this if i2c.write_read(0x19, &[0x32], &mut data).is_ok() {

I get this

x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107                                                    
x: 13107, y: 13107, z: 13107       ```

[therealprof]

I find it rather likely that this is caused by different sensors used in different revisions of the board. Rev 1.3 (and below) use MAG3110 (cf. https://tech.microbit.org/hardware/previous-revision/), while Rev 1.5 uses LSM303AGR and potentially in the future FXOS8700CQ, cf. https://tech.microbit.org/hardware/

[bodagovsky]

I still can’t get, why I have always the same values? Am I doing something wrong? I am using addresses from here https://tech.microbit.org/hardware/i2c/

[therealprof]

The driver you're using is MAG3110 only, I don't know how much the LSM303AGR register interface differs but it's highly likely to not work with the unmodified MAG3110 driver.

[robyoung]

there is now a magnetometer example that runs on V1.5 and V2