I am having a hard time getting the correct value that I need. I get from my characteristic vales from:
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor ...
I can read and print off the values with:
let values = characteristic.value
for val in values! {
print("Value", num)
}
This gets me:
"Value 0" // probe state not important
"Value 46" // temp
"Value 2" // see below
The problem is that the temp is not 46. Below is a snippet of instructions on how I need to convert the byte to get the actual temp. The actual temp was around 558 ºF. Here are a part of the instructions:
Description: temperature data that is valid only if the temperature stat is normal
byte[1] = (unsigned char)temp;
byte[2] = (unsigned char)(temp>>8);
byte[3] = (unsigned char)(temp>>16);
byte[4] = (unsigned char)(temp>>24);
I can't seem to get the correct temp? Please let me know what I am doing wrong.
According to the description, value[1] ... value[4] are the least significant to most significant bytes of the (32-bit integer) temperature, so this is how you would recreate
that value from the bytes:
if let value = characteristic.value, value.count >= 5 {
let tmp = UInt32(value[1]) + UInt32(value[2]) << 8 + UInt32(value[3]) << 16 + UInt32(value[4]) << 24
let temperature = Int32(bitPattern: tmp)
}
The bit-fiddling is done in unsigned integer arithmetic to avoid an overflow. Assuming that the temperature is a signed value, this value is then converted to a signed integer with the same bit representation.