Why are you initializing the const items using as_byte_slice()? Have you tried just making a simple array?
```rust
pub const START_PERIODIC_MESUREMENT: [u8, 2] = [0x21, 0xb1];
pub const IPREAD_MEASUREMENTOLA: [u8, 2] = [0xec, 0x05];
pub const STOP_PERIODIC_MEASUREMENT: [u8, 2] = [0x3f, 0x86];
```