The GPIOs of MCF8315 are connected as shown in
Figure 3-2.
- SPEED pin is connected to MSPM0L1306 for
speed control. This pin can instead be directly connected to a (0-3)V input for
speed control using analog speed control mode.
- SCL, SDA pins are connected to MSPM0L1306
with pull-up resistors to AVDD for I2C communication.
- FG pin is connected to MSPM0L1306 with
external pull-up resistor to AVDD. FG indicates the motor speed. The external
pull-up resistor can be removed when internal pull-up resistor is enabled
through EEPROM.
- DIR pin is connected to AGND (through an
optional pull-down resistor) since the pin is unused. In this case, direction of
rotation can set using EEPROM.
- BRAKE pin is connected to MSPM0L1306 for
brake operation. This is an active high signal and when BRAKE pin is set high,
MCF8315 decelerates the motor to user configured speed threshold and then
applies low side brake to quickly bring the motor to a stop.
- DACOUT1, DACOUT2, DACOUT2/SOX are output
pins that are connected to test points for monitoring signals.
- EXT_WD, EXT_CLK pins are unused and hence
left floating. EXT_WD, EXT_CLK can also be connected to AGND directly when
unused.
- nFAULT pin is connected to MSPM0L1306.
This is an active low, open drain fault indicator output and needs internal
pull-up resistor to AVDD to be enabled through EEPROM for fault indication.
- DRVOFF pin is an active high input signal
that is connected to MSPM0L1306 and can be used to immediately disconnect power
to the motor.
- ALARM pin is left floating since the pin
is unused.
- NC pins are connected to AGND along with
thermal pad and all other ground pins (DGND, GND_BK, PGND, AGND) for better
thermal performance.