Hardware and layout
UM1079
18/38
DocID018789 Rev 4
Three pairs of I/O ports are assigned to the linear touch sensor / touchkeys. Each pair must
belong to the same analog switch group:
•
PA6, PA7 (group 2)
•
PC4, PC5 (group 9)
•
PB0, PB1 (group 3)
To minimize the noise, these pairs are dedicated to the linear touch sensor / touchkeys and
are not connected to external headers.
To design a touch sensing application, refer to the following documentation and firmware:
•
For details concerning I/O ports, refer to the STM32L152RCT6 datasheet.
•
For information on software development, see discovery application software on
www.st.com/mcu.
•
For more detail concerning touch sensing application design and layout, refer to
Guidelines for designing touch sensing applications with surface sensors
(AN4312).
•
STM32 touch sensing library available from www.st.com/mcu
4.7 Built-in
I
DD
measurement circuit
The 32L152CDISCOVERY built-in I
DD
measurement circuit allows to measure the
consumption of the STM32L152RCT6 and to display the value on the LCD glass while the
MCU is in Run or Low-power modes.
•
JP1 ON: the STM32L152RCT6 is powered through the I
DD
measurement circuit
(default).
•
JP1 OFF: the STM32L152RCT6 is directly powered. The I
DD
measurement circuit is
bypassed.
Note:
When jumper JP1 is removed, the current consumption of the
STM32L152RCT6
can be
measured by connecting an ammeter between jumper pin 1 and pin 2 of JP1.
To perform the I
DD
measurement by the MCU itself, the circuit shown in
Figure 10
is
implemented on the 32L152CDISCOVERY. The solder bridges
SB1, SB2 and SB14 must
be closed and JP1 must be ON.The low IDD range procedure (see
Section 4.7.2
) is
recommended when the MCU is in Low-power mode and the IDD current does not exceed
60
μ
A. The high IDD range procedure (see
Section 4.7.1
)is applicable when the MCU
operates in Run mode and can sink up to 30 mA.
