Page 428 - ARM Based Microcontroller Projects Using MBED

414 17. STM32 NUCLEO EXPANSION BOARDS

FIG. 17.8 Typical display.

humidity, temperature, and pressure, respectively. The dew point is calculated using the fol-
lowing formula by Magnus:

ð
G ¼ Ln RH=100Þ + b TÞ= c + TÞ
ð
ð
ð
Dew Point ¼ c G= b gÞ
where Ln is the logarithm to base 2, RH is the relative humidity as a percentage, T is the
ambient temperature in degree Centigrade, Dew Point is in degree Centigrade, and b and c are
the following constants:
b ¼ 17:67, c ¼ 243:5

For example, if RH¼10%, T¼25°C then the dew point is
ð
ð
ð
G ¼ Ln 10=100Þ +17:67 25Þ= 243:5+25Þ
or
G ¼ 0:657
ð
Dew Point ¼ 243:5 0:657= 17:67 + 0:657Þ
which gives, Dew Point¼ 8.72°C
A heading is displayed followed by all the four parameters. The display is repeated every
15s. Fig. 17.8 shows a typical display from the program.

17.7 MULTIFUNCTIONAL EXPANSION BOARD
(X-NUCLEO-IKA01A1)

This expansion board (Fig. 17.9) is based on operational amplifiers which can be used as an
analog front end. The board contains a micropower and nanopower operational amplifiers.
The basic features of this expansion board are as follows:

• seven predefined configurations: instrumentation amplifier, current sensing photodiode,
ultraviolet current sensing, buffer, full wave rectifier, constant current LED driver,
window comparator
• prototyping area on board
• Arduino UNO R3 connector compatible