You have hit a bug in the implementation of parseFloat().

This function reads the number you send as an integer, ignoring the decimal point, and stores it in a long. It then multiplies it by a scaling factor (a power of 0.1) in order to get the correct value. The problem is, if you provide too many significant digits, the integer overflows, and you get garbage. For example "44.64978683" is interpreted as

(long) 4464978683 * 0.00000001

but (long) 4464978683 overflows and rolls over to 170011387, hence the result you get.

Simple workaround: do not provide so many significant digits. They are irrelevant anyway given the resolution of a float.

Edit: I did not find any bug report for this issue, so I submitted my own to the Arduino dev team.

You have hit a bug in the implementation of parseFloat().

This function reads the number you send as an integer, ignoring the decimal point, and stores it in a long. It then multiplies it by a scaling factor (a power of 0.1) in order to get the correct value. The problem is, if you provide too many significant digits, the integer overflows, and you get garbage. For example "44.64978683" is interpreted as

(long) 4464978683 * 0.00000001

but (long) 4464978683 overflows and rolls over to 170011387, hence the result you get.

Simple workaround: do not provide so many significant digits. They are irrelevant anyway given the resolution of a float.

Edit: I did not find any bug report for this issue, so I submitted my own to the Arduino dev team.

Update: Per request of a maintainer, I submitted a pull request with a failing unit test revealing this bug. We then worked on a fix, which has now been merged to master. It should be published on the next release of ArduinoCore-API.

Note, however, that the AVR core does not yet use the common API repository. In the meantime, it may be worth submitting a pull request to ArduinoCore-avr that cherry-picks the fix from ArduinoCore-API.

You have hit a bug in the implementation of parseFloat().

This function reads the number you send as an integer, ignoring the decimal point, and stores it in a long. It then multiplies it by a scaling factor (a power of 0.1) in order to get the correct value. The problem is, if you provide too many significant digits, the integer overflows, and you get garbage. For example "44.64978683" is interpreted as

(long) 4464978683 * 0.00000001

but (long) 4464978683 overflows and rolls over to 170011387, hence the result you get.

Simple workaround: do not provide so many significant digits. They are irrelevant anyway given the resolution of a float.

You have hit a bug in the implementation of parseFloat().

This function reads the number you send as an integer, ignoring the decimal point, and stores it in a long. It then multiplies it by a scaling factor (a power of 0.1) in order to get the correct value. The problem is, if you provide too many significant digits, the integer overflows, and you get garbage. For example "44.64978683" is interpreted as

(long) 4464978683 * 0.00000001

but (long) 4464978683 overflows and rolls over to 170011387, hence the result you get.

Simple workaround: do not provide so many significant digits. They are irrelevant anyway given the resolution of a float.

Edit: I did not find any bug report for this issue, so I submitted my own to the Arduino dev team.