TMC8462 Datasheet • Document Revision V1.4 • 2018-May -09
185 / 204
7.20 MFC IO Emergency Switch Input
The MFC IO block offers a dedicated emergency switch input called MFC_NES. It is low active.
It is used to set specific MFCIOxx outputs to a a configurable safe state in case of emergency.
The MFC_NES pin has weak internal pull-down resistor. A microcontroller or another circuit must actively
drive a high level at MFC_NES for normal operation.
The emergency switch input MFC_NES is only active if it is masked in the MFCIO_IRQ_CFG register at bit 23.
Otherwise it is ignored.
If MFC_NES triggers (low level), the respective outputs take their configured safe values. The internal
emergency switch flag remains set in register MFCIO_IRQ_FLAGS even when the external pin MFC_NES is
already driven high again.
MFC_NES has impact on the following functional units and outputs:
•
MFC IO PWM block: the PWM high and low side gate outputs are set to a defined configurable safe
off-state.
•
MFC IO GPIO block: all GPIOs that are configured as output ports via the crossbar are set to a defined
configurable safe off-state.
• MFC IO Step and Direction block: the step outputs and internal step counters freeze.
• The MFCIO_IRQ signal will be triggered.
Note
The emergency flag can only be unset be either doing a reset or by actively
writing 2 times into the MFCIO_IRQ_CFG register at bit position 23. Thereby, the
existing IRQ mask at bit 23 must first be set to zero and then set back to 1 again.
This way, the internal emergency flag is unset. This can be done either by the
local application controller or by the EtherCAT master if it has access to register
MFCIO_IRQ_CFG.
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