AM6421 datasheet(214/237 Pages) TI

214 / 237 page

For more information, see Enhanced Pulse Width Modulation (EPWM) Module section in Peripherals chapter in

the device TRM.

8.4.2.8 ELM

The Error Location Module (ELM) is used with the GPMC. Syndrome polynomials generated on-the-fly when

reading a NAND flash page and stored in GPMC registers are passed to the ELM. A host processor can then

correct the data block by flipping the bits to which the ELM error-location outputs point.

When reading from NAND flash memories, some level of error-correction is required. In the case of NAND

modules with no internal correction capability, sometimes referred to as bare NANDs, the correction process is

delegated to the memory controller. ELM can be also used to support parallel NOR flash or NAND flash.

The General-Purpose Memory Controller (GPMC) probes data read from an external NAND flash and uses this

to compute checksum-like information, called syndrome polynomials, on a per-block basis. Each syndrome

polynomial gives a status of the read operations for a full block, including 512 bytes of data, parity bits, and an

optional spare-area data field, with a maximum block size of 1023 bytes. Computation is based on a Bose-

Chaudhuri-Hocquenghem (BCH) algorithm. The ELM extracts error addresses from these syndrome

polynomials.

For more information, see Error Location Module (ELM) section in Peripherals chapter in the device TRM.

8.4.2.9 ESM

The Error Signaling Module (ESM) aggregates safety-related events and/or errors from throughout the device

into one location. It can signal both low and high priority interrupts to a processor to deal with a safety event

and/or manipulate an I/O error pin to signal an external hardware that an error has occurred. Therefore an

external controller is able to reset the device or keep the system in safe, known state.

For more information, see Error Signaling Module (ESM) section in Peripherals chapter in the device TRM.

8.4.2.10 EQEP

The Enhnanced Quadrature Encoder Pulse (EQEP) peripheral is used for direct interface with a linear or rotary

incremental encoder to get position, direction and speed information from a rotating machine for use in high

performance motion and position control system. The disk of an incremental encoder is patterned with a single

track of slots patterns. These slots create an alternating pattern of dark and light lines. The disk count is defined

as the number of dark/light line pairs that occur per revolution (lines per revolution). As a rule, a second track is

added to generate a signal that occurs once per revolution (index signal: QEPI), which can be used to indicate

an absolute position. Encoder manufacturers identify the index pulse using different terms such as index,

marker, home position and zero reference.

To derive direction information, the lines on the disk are read out by two different photo-elements that "look" at

the disk pattern with a mechanical shift of 1/4 the pitch of a line pair between them. This shift is realized with a

reticle or mask that restricts the view of the photo-element to the desired part of the disk lines. As the disk

rotates, the two photo-elements generate signals that are shifted 90 degrees out of phase from each other.

These are commonly called the quadrature QEPA and QEPB signals. The clockwise direction for most encoders

is defined as the QEPA channel going positive before the QEPB channel and vise versa.

The encoder wheel typically makes one revolution for every revolution of the motor or the wheel may be at a

geared rotation ratio with respect to the motor. Therefore, the frequency of the digital signal coming from the

QEPA and QEPB outputs varies proportionally with the velocity of the motor. For example, a 2000-line encoder

directly coupled to a motor running at 5000 revolutions per minute (rpm) results in a frequency of 166.6 KHz, so

by measuring the frequency of either the QEPA or QEPB output, the processor can determine the velocity of the

motor.

For more information, see Enhanced Quadrature Encoder Pulse (EQEP) Module section in Peripherals chapter

in the device TRM.

8.4.2.11 GPIO

The general-purpose input/output (GPIO) peripheral provides dedicated general-purpose pins that can be

configured as either inputs or outputs. When configured as an output, user can write to an internal register to

AM6442, AM6441, AM6421

AM6412, AM6411

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