FXTH870xD
Sensors
10
Freescale Semiconductor, Inc.
2.3.9
PTA[3:2] Pins
The PTA[3:2] pins are general purpose I/O pin. These two pins can be configured as normal bidirectional I/O pin with
programmable pullup or pulldown devices and/or wakeup interrupt capability; or one or both can be connected to the two input
channels of the Timer Pulse Width (TPM1) module. The pulldown devices can only be activated if the wakeup interrupt capability
is enabled. User software must configure the general purpose I/O pins so that they do not result in “floating” inputs as described
in
. PTA[3:2] map to Keyboard Interrupt function bits [3:2].
2.3.10
BKGD/PTA4 Pin
The BKGD/PTA4 pin is used to place the FXTH870xD in the BACKGROUND DEBUG mode (BDM) to evaluate MCU code and
to also transfer data to/from the internal memories. If the BKGD/PTA4 pin is held low when the FXTH870xD comes out of a power-
on reset the device will go into the ACTIVE BACKGROUND DEBUG mode (BDM).
The BKGD/PTA4 pin has an internal pullup device and can connected to V
DD
in the application unless there is a need to enter
BDM operation after the device as been soldered into the PWB. If in-circuit BDM is desired the BKGD/PTA4 pin can be left
unconnected, but should be connected to V
DD
through a low impedance resistor (<10 k
) which can be over-driven by an
external signal. This low impedance resistor reduces the possibility of getting into the debug mode in the application due to an
EMC event.
2.3.11
RESET Pin
The RESET pin is used for test and establishing the BDM condition and providing the programming voltage source to the internal
FLASH memory. This pin can also be used to direct to the MCU to the reset vector as described in
.
The RESET pin has an internal pullup device and can connected to V
DD
in the application unless there is a need to enter BDM
operation after the device as been soldered to the PWB. If in-circuit BDM is desired the RESET pin can be left unconnected; but
should be connected to V
DD
through a low impedance resistor (<10 k
) which can be over-driven by an external signal. This low
impedance resistor reduces the possibility of getting into the debug mode in the application due to an EMC event.
Activation of the external reset function occurs when the voltage on the RESET pin goes below 0.3 x V
DD
for at least 100 nsec
before rising above 0.7 x V
DD
as shown in
Figure 7
.
Figure 7. RESET Pin Timing
2.3.12
PTB[1:0] Pins
The PTB[1:0] pins are general purpose I/O pins. These two pins can be configured as nominal bidirectional I/O pins with
programmable pullup devices. User software must configure the general purpose I/O pins so that they do not result in “floating”
inputs as described in
RESET
0.7 V
DD
0.3 V
DD
> 100 nsec
Reset
Initiated
Содержание FXTH870 D Series
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