The driver initializes communication with the encoder using the HELLO command
The encoder wakes up and establishes EnDAT3 communication (may take up to 300ms)
The diagnostic presents a user-friendly menu interface
Users can select from foreground commands, background commands, continuous mode, or periodic mode

Key Improvements Over EnDAT 2.2

EnDAT3 provides several significant enhancements:

Higher Data Rates: Up to 25 Mbps (current implementation supports 12.5 Mbps, compared to EnDAT 2.2's maximum of ~16 MHz with legacy encoding)
Manchester Encoding: Self-clocking data transmission for improved reliability
Enhanced Safety: Additional safety features and error detection mechanisms
Bidirectional Background Communication: Parallel data exchange alongside position data
Low Priority Frames (LPF): Flexible send lists for transmitting additional encoder information
Frame Structure: Organized into High Priority Frame (HPF), Low Priority Header (LPH), and Low Priority Frame (LPF)

EnDAT3 Protocol Overview

System Architecture

The EnDAT3 system consists of multiple layers working together to provide position encoder communication:

EnDAT3 System Design - Data Flow Diagram

Communication Frame Structure

EnDAT3 communication uses a structured frame format consisting of three main components:

High Priority Frame (HPF)
- Contains position data (up to 48 bits)
- Status byte with F (Error), W (Warning), and HPFV (HPF Valid) flags
- 8-bit CRC for data integrity
- Always transmitted in every cycle
Low Priority Header (LPH)
- 8-bit status field indicating communication state (IDLE, RX_START, RX_LAST, BUSY)
- Number of LPF frames following (num_lpf field)
- 8-bit CRC for header integrity
- Manages background communication flow
Low Priority Frame (LPF)
- Contains additional encoder data (48 bits per frame)
- Configurable via send lists (DATA0-DATA7 commands)
- 8-bit Frame ID (FID) for identification
- Separate 8-bit CRC per frame
- Multiple LPF frames can be transmitted per cycle

Manchester Encoding

EnDAT3 uses Manchester encoding for data transmission:

Self-clocking: Clock information embedded in data signal
Each bit period divided into two half-bits
Logic '1': High-to-Low transition in middle of bit period
Logic '0': Low-to-High transition in middle of bit period
Provides robust noise immunity and DC-free transmission
Requires 8x oversampling for reliable decoding

Command Preamble and Postamble

Each EnDAT3 command transmission includes:

Preamble: Minimum 25 halfbits of alternating pattern for synchronization
Command Data: Manchester-encoded foreground and background operation codes
Postamble: 4 halfbits to complete the transmission

Data Rates

EnDAT3 protocol specification defines two primary data rates:

12.5 Mbps: 25 MHz clock (2 halfbits per clock cycle) - Supported
25 Mbps: 50 MHz clock (2 halfbits per clock cycle) - Not currently supported

Note: Current implementation supports only 12.5 Mbps data rate. The RATE command is available in the diagnostic menu but changing to 25 Mbps is not functional in this release.

Features Demonstrated

The diagnostic application demonstrates:

Foreground Communication

DATA0-DATA7: Activate different LPF send lists (configurable encoder data)
DATA: General data with background data
DATANOP: Data without background data
RESET: Encoder reset functionality (hard reset or soft reset)
CLEAR: Reset encoder states (F, W, REF flags)
ECHO: Measure propagation time for cable delay compensation
RATE: Data rate configuration command (NOTE: only 12.5 Mbps is currently supported)
HELLO: Initialization sequence to wake up encoder on power-up and establish EnDAT3 communication

Background Communication

NOP: No operation
READ: Read from encoder memory
WRITE: Write to encoder memory
RECONFIGURE: Reconfigure encoder parameters
AUTH: Authenticate with user level and password
PROTECT: Set memory protection levels
SETPASS: Set password for user level
LOCATE: Encoder location function

Operating Modes

Host trigger mode: Command-driven communication
Periodic CMP/CAP trigger mode: Automatic position updates via IEP compare/capture events

The EnDAT3 diagnostic application supports two types of periodic trigger modes for continuous position sampling as described in Operating Modes.

CMP Mode (Compare Event Mode)

Implementation: UART command 3 demonstrates this mode using position command ENDAT3_REQ_DATA0
Configuration: Uses a user-defined compare value to trigger sampling events
IEP Counter Reset: Uses CMP0 by default (skip if reset is handled differently)
Notification: Firmware triggers an Arm® Cortex®-R5F interrupt after receiving encoder response

CAP Mode (Capture Event Mode)

Implementation: UART command 4 demonstrates this mode using position command ENDAT3_REQ_DATA0
XBAR Configuration for CAP6/CAP7 (LATCH_IN0/LATCH_IN1)
- This example configures the XBAR for routing EPWM SYNC OUT as input to CAP using SysConfig
- Customization: XBAR settings can be modified for alternative inputs
- NOTE: XBAR routing configuration is optional if not needed
NOTE: When using different CAP events instead of the ones used in SDK example, ensure all related configurations (source selection, signal routing, etc.) are properly done.
Notification: Firmware triggers an R5F interrupt after receiving encoder response

Important Notes for Periodic Mode

Initialization: Send the command once in host trigger mode before switching to periodic mode. Refer the endat3_process_periodic_command() function in the example code, which calls required functions for ENDAT3_REQ_DATA0.
CMP Resource Allocation
- Avoid using CMP0 if it's already used to IEP counter reset
- Avoid using CMP1/CMP2 if they're used to SYNC OUT generation
- Avoid sharing CMP events across different channels or instances of EnDAT3 or other encoders. Each CMP event must be assigned exclusively to a single encoder channel.
Modifying Commands in Periodic Mode
- Default: ENDAT3_REQ_DATA0 is used by default
- To use a different command:
  - First modify the endat3_process_periodic_command() function in example code
  - Before switching to periodic mode, send this command once using in host trigger mode
  - Ensure all prerequisite APIs are called to properly set up command data. Refer the endat3_diagnostic_main() function in the example code to identify all required API calls for specific command.

Data Display

High Priority Frame (HPF): Position data and status
Low Priority Header (LPH): Frame count and communication status
Low Priority Frame (LPF): Additional data with Frame ID
CRC verification for all frame types
Error and warning flag interpretation

Features Not Supported

In general, peripherals or features not mentioned as part of "Features Demonstrated" section are not supported in this release, including the below:

25 Mbps Data Rate: Currently only 12.5 Mbps is supported and tested
Multi-Channel Configuration: Only single channel operation is supported
Daisy Chain Topology: Daisy chaining multiple encoders on a single interface is not supported

Limitations

This section describes known limitations of the current implementation:

The 25 Mbps data rate requires higher clock frequencies and tighter timing constraints. Current implementation is validated for 12.5 Mbps operation only.
Multi-channel support would require additional PRU cores or time-multiplexing, which is not implemented in the current firmware architecture.
Daisy chain configuration requires special handling of multiple encoder responses in series, which is not supported in this release.

SysConfig Features

SysConfig can be used to configure different settings for EnDAT3. Refer SysConfig Features section for more details.

Channel Selection In SysConfig

The SysConfig GUI allows easy configuration of the EnDAT3 interface channels. Below are examples showing channel selection for different platforms:

EnDAT3 SysConfig - Channel Selection for AM263Px

Important Files and Directory Structure

Folder/Files	Description
${SDK_INSTALL_PATH}/examples/position_sense/endat3_diagnostic
endat3_diagnostic.c	EnDAT3 diagnostic application
endat3_periodic_trigger.h	Periodic trigger mode header
endat3_periodic_trigger.c	IEP timer configuration for periodic mode
${SDK_INSTALL_PATH}/source/position_sense/endat3
firmware/	Folder containing EnDAT3 firmware sources
driver/	EnDAT3 driver implementation
include/	EnDAT3 API header files

Supported Combinations

Parameter	Value
CPU + OS	r5fss0-0 freertos
ICSSM	ICSSM0
PRU	PRU0
Toolchain	ti-arm-clang
Board	am263px-lp
Example folder	examples/position_sense/endat3_diagnostic/single_channel

Single Channel with Single PRU Example

This example supports one EnDAT3 channel using one PRU. In this example:

1 EnDAT3 driver instance and corresponding SysConfig EnDAT3 module instance is used.

Steps to Run the Example

Other than the basic EVM setup mentioned in EVM Setup , the following additional hardware is required to run this demo:

Hardware Prerequisites with LP-AM263P

Hardware Setup

Hardware Setup (Using BP-AM2BLDCSERVO Booster Pack and LP-AM263P)

EnDAT3 Hardware Setup with LP-AM263P and BP-AM2BLDCSERVO Booster Pack

EnDAT3 Connector Pinout

S.No	Booster Pack Axis I Pin	EnDAT3 Connector No. (15 pins)
1	VENCODER	4, 12
2	GND	2, 10
3	DATAP1 (Data +)	8
4	DATAM1 (Data -)	15

LP-AM263P Jumper Configuration

Designator	ON/OFF	Description
J13	Pin 1-2 Connected	3V3 Supply to Booster Pack
J14	Pin 1-2 Connected	5V0 Supply to Booster Pack

Pin Configuration (AM263Px)

The EnDAT3 interface on AM263Px uses ICSSM-PRU0 with the following pin mapping:

Signal	PRU GPIO	LaunchPad Pin	Description
TX (Data Out)	PR0_PRU0_GPIO3	Configured via SysConfig	Encoder command data output
TX_CLK (Clock Out)	PR0_PRU0_GPIO4	Configured via SysConfig	Clock signal to encoder
TX_EN (Transmit Enable)	PR0_PRU0_GPIO5	Configured via SysConfig	RS485 driver enable
RX (Data In)	PR0_PRU0_GPIO10	Configured via SysConfig	Encoder response data input
ENC0_EN (Channel Enable)	GPIO (SDFM0_D1/D13)	Controlled by R5F	Enable Booster Pack Axis 1 encoder voltage

BP-AM2BLDCSERVO Booster Pack Jumper Configuration

Note

To enable VSENSOR1, BoosterPack pin J8.73 must be set high (In this example, this pin is configured in GPIO mode and pulled high)

Designator	ON/OFF	Description
J11	OFF	VSENSE/ISENSE select
J13	OFF	VSENSE/ISENSE select
J17	Pin 1-2 Connected	SDFM Clock Feedback Select
J18/J19	J18 installed: sets VSENSOR1 to 12.0V	Axis 1: Encoder/Resolver Voltage Select
J20/J21	J20 installed: sets VSENSOR2 to 12.0V	Axis 2: Encoder/Resolver Voltage Select
J22	OFF	Axis 1: Manchester Encoding Select
J23	OFF	Axis 2: Manchester Encoding Select
J24	OFF	Axis 1: RS485/DSL MUX
J25	OFF	Axis 2: RS485/DSL MUX
J26	OFF	VSENSE/ISENSE Select
J27	OFF	Encoder and SDFM Paths Select
J28	ON	AM243/AM263 Mode

Build, Load and Run

When using CCS projects to build, import the CCS project and build it using the CCS project menu (see Using SDK with CCS Projects ).
When using makefiles to build, note the required combination and build using the make command (see Using SDK with Makefiles )
Launch a CCS debug session and run the executable, see CCS Launch, Load and Run
Refer to the UART terminal for user interface menu options.

Application Flow

Application Flowchart

The following flowchart shows the complete application flow from initialization to command execution:

EnDAT3 R5F Application Flowchart

Initialization Sequence

Hardware Initialization
- Open drivers (UART for console)
- Initialize PRU-ICSS subsystem
- Initialize I2C driver for I/O expander communication
- Configure I/O expander (TCA6408/TCA6416) for booster pack MUX control
- Enable GPIO for booster pack channel selection (if applicable)
- Configure GPIO pins for encoder channel enable signals
EnDAT3 Interface Initialization
- Initialize EnDAT3 interface with endat3_init()
- Load PRU firmware binary to selected PRU core
- Configure PRU-ICSS INTC (Interrupt Controller) for event mapping
- Initialize shared memory interface between R5F and PRU
- Run PRU firmware
- Set to host trigger mode by default (opmode = 1)
- Clear any previous trigger states
- Wait for encoder to be ready (up to 1 second timeout)
EnDAT3 Communication Establishment
- Send HELLO command to encoder with background data 0x2222
- Encoder wakes up and establishes EnDAT3 communication
- Wait for initialization to complete (up to 300ms)
- Verify successful initialization by checking encoder response
- Configure initial data rate (typically starts at 12.5 Mbps)
Main Menu Loop
- Display command type selection menu
- Wait for user input via UART
- Execute selected command type
- Process and display results

Command Type Selection

The application presents four command type options via the UART terminal interface:

EnDAT3 Main Menu - Command Type Selection

The application presents four command type options:

Foreground Communication (0)
- Single command execution
- Position data with optional background data
- Various encoder control commands
Background Communication (1)
- Multi-cycle operation
- Memory read/write operations
- Parameter configuration
- Authentication and protection
Continuous Position Fetch (2)
- Non-stop position updates
- Real-time data display
- User-initiated stop
Periodic Trigger Mode (3 or 4)
- Two modes: CMP (compare event) and CAP (capture event)
- CMP mode: IEP timer-driven updates at regular intervals
- CAP mode: External signal-driven position capture
- Deterministic cycle time
- Automatic position requests

Foreground Communication Commands

After selecting foreground communication, the menu presents:

EnDAT3 Foreground Communication Menu

The foreground menu presents:

Select command for endat3 foreground communication:
DATA0 (Activate LPF send list 0)
DATA1 (Activate LPF send list 1)
DATA2 (Activate LPF send list 2)
DATA3 (Activate LPF send list 3)
DATA4 (Activate LPF send list 4)
DATA5 (Activate LPF send list 5)
DATA6 (Activate LPF send list 6)
DATA7 (Activate LPF send list 7)
DATA (General data with BGD)
DATANOP (Data without BGD)
RESET (Encoder reset)
CLEAR (Resetting of states)
ECHO (Echo for measuring propagation time)
RATE (Set data transfer rate)
HELLO (Switch to EnDat 3 mode)

Execution Flow:

Parse user selection to command code
Set foreground operation code
Set background operation code to NOP
Prompt for additional parameters (if needed)
Set background data (for RESET, CLEAR, ECHO, RATE, HELLO)
Send command and wait for response
Display results with error checking

Example - HELLO Command:

User selects: 15
Application sets:
  - foreground_op_code = ENDAT3_REQ_HELLO
  - background_data[0] = 0x2222 (fixed value)
  - expected_tx_frames = 1
Sends command and receives response
Displays: "Successfully established EnDat3 communication"
Note:
  - HELLO must be sent after encoder power-up to wake up the encoder
  - HELLO must be sent after each baud rate change via RATE command
  - May take up to 300ms to complete
  - Establishes EnDAT3 communication and synchronization

Example - RESET Command:

User selects: 11
Menu prompts: "Select reset type:"
  1: Hard Reset (0xBBBB)
  2: Other (Enter custom value)
User selects: 1
Application sets:
  - foreground_op_code = ENDAT3_REQ_RESET
  - background_data[0] = 0xBBBB
Sends command and receives response
Waits additional 302ms for encoder restart

Background Communication Commands

After selecting background communication, the menu presents:

EnDAT3 Background Communication Menu

The background menu presents:

Select background request operation:
No Operation (NOP)
Read from encoder memory
Write to encoder memory
Reconfigure parameters
Authentication
Set protection
Set password
Locate function

Multi-Cycle Execution:

Background communication requires multiple command cycles depending on LPH status:

LPH Status	State	Cycles Required	Behavior
0	IDLE	4	Send request in 4 cycles, response in 4th cycle
1	RX_START	6	Send request for 2 NOP cycles, then send request acc. to IDLE state
2	RX_LAST	5	Send request for 1 NOP cycle, then send request acc. to IDLE state
3	BUSY	N/A	Wait, cannot send request

Example - READ Operation:

User selects: 2 (Read)
Menu prompts:
  "Enter number of words to read:" -> 1
  "Enter address (MSB byte):" -> 0xA1
  "Enter address (LSB 2 bytes):" -> 0x0000
 
Application checks LPH status:
  If IDLE (0):
    endat3_handle_background_command_request(ch, 0, 4, READ, 0xA1, 0x0000, 1)
    Sends 4 command cycles with proper timing
 
Response processing:
  HPF: Position data
  LPH: Indicates 1 LPF frame following
  LPF[0]: Contains read data at address 0xA10000

Example - AUTH Operation:

User selects: 5 (Authentication)
Menu prompts:
  "Enter user level (0-255):" -> 1 (OEM2)
  "Enter password (hex, up to 32 bits):" -> 0x12345678
 
Application formats:
  addr_msb = 1 (user level)
  addr_lsb = (0x12345678 >> 16) & 0xFFFF = 0x1234
  data = 0x12345678 & 0xFFFF = 0x5678
 
Sends AUTH command with multi-cycle protocol
Response indicates authentication success/failure

Continuous Position Fetch Mode

When user selects continuous mode (option 2):

Setup:
- Create background task to monitor Enter key
- Set position loop status to START
- Display instructions to user
Main Loop:
while (loop_status == START):

Send DATA0 command

Wait for response

If HPF data valid:

Extract position (30-bit value)

Calculate angle = position * 360.0 / 2^30

Display: "Position: 0x%x, Angle: %f degrees"

Delay 1ms

Check if user pressed Enter to stop
Stop:
- User presses Enter
- Background task sets loop_status to STOP
- Main loop exits
- Return to main menu

Periodic Trigger Mode

When user selects periodic mode (option 3 or 4):

CMP Mode Configuration:
Menu prompts:

"Enter IEP reset cycle count (must be greater than EnDat3 cycle time including timeout period, in IEP cycles)" -> iep_reset_count

"Enter IEP trigger time(must be less than or equal to IEP reset cycle, in IEP cycles):" -> periodic_trigger_count

Validation: periodic_trigger_count <= iep_reset_count

CMP Mode Example Configuration:
PRU Core Clock: 200 MHz (AM261x/AM263Px) or 300 MHz (AM243x)

Desired Position Update Rate: 1 kHz (1ms period)

For 200 MHz IEP clock:

iep_reset_count = 200 MHz / 1 kHz = 200,000 cycles

periodic_trigger_count = 10,000 cycles (trigger after reset)

For 300 MHz IEP clock:

iep_reset_count = 300 MHz / 1 kHz = 300,000 cycles

periodic_trigger_count = 10,000 cycles (trigger after reset)

CMP Mode Timing Diagram:
Counter: 0 ----------> CMPy ----------------------> CMP0 --> 0

| | | |

Reset Trigger Reset Trigger

(CMPy) (CMP0) (CMPy)

Command Sent Command Sent
CAP Mode Configuration:

Periodic CAP mode cycle time will be equal to EPWM SYNC OUT frequency. NOTE: In SysConfig, EPWM and EPWM to IEP LATCH XBAR configuration must be done.

Operating Mode and firmware setup:
- Update the operating mode of firmware using endat3_set_operating_mode() API call
- Pre-configure command (DATA0)
- Set expected TX frame count to 1
- Release start trigger to firmware
- CMP/CAP events automatically trigger commands
IEP Setup (CMP Mode):
- Disable IEP counter
- Configure IEP CMP0 for counter reset (defines period)
- Configure IEP CMPy for trigger event (CMPy selected in SysConfig)
- Enable IEP counter
IEP Setup (CAP Mode):
- Disable IEP counter
- SysConfig configures XBAR to route EPWM SYNC OUT to CAP input
- Configure IEP CAPy for capture event (CAPy selected in SysConfig)
- Enable IEP counter
IRQ Callback:

In periodic mode, firmware generates R5F interrupt after encoder response is ready.

Data Display Loop:
while (loop_status == START):

Wait for IRQ count to increment

Wait for firmware busy flag to clear

Receive response

If successful and HPF valid:

Extract position and angle

Display values

Check if user pressed Enter to stop
Stop and Cleanup:
- Call endat3_stop_periodic_mode() to stop IEP timer and disable interrupts
- Set firmware back to host trigger mode (opmode = 1)
- Wait for mode switch to complete
- Return to main menu

Response Display

Position Information Display

For successful DATA commands, the application displays:

Position Information:
 HPF Status: 0x20
 - HPF data valid (HPFV bit set)
 Position Data: 0x12345678
 CRC: 0xA5
 Additional Information:
 LPH Status (communication Status): 0x2
 LPF Status: 0x10
 LPF Data: 0x01 0x02 0x03 0x04 0x05 0x06
 LPF CRC: 0x5A

HPF Status Flags:

Bit 0 (F): Error flag
Bit 1 (W): Warning flag
Bit 5 (HPFV): HPF data valid
Bit 6 (RM): Absolute value available

Error Status Display

When errors are detected:

HPF and LPH Status:
 HPF Status: 0x01
 LPH Status: 0x00
 Error Code: 0x1234
 Description: Voltage supply too low
 Recommended action: Check encoder power supply

The application uses endat3_get_error_code(), endat3_get_error_description() and endat3_get_error_action() to provide detailed error information including description and recommended action.

Firmware Flow

The EnDAT3 firmware implements the low-level protocol handling on the PRU cores. The firmware consists of transmit and receive processing paths:

Firmware Transmit Flow

EnDAT3 Firmware Transmit Processing Flow

Firmware Receive Flow

EnDAT3 Firmware Receive Processing Flow

The firmware handles Manchester encoding/decoding, frame assembly/parsing, CRC calculation, and timing control at the PRU level.

EnDat3 Debug Guide

This section describes how to debug the EnDAT3 application, including a guide to debugging the EnDAT3 example and firmware.

Common Debugging Steps

Several common debugging procedures apply to EnDAT3:

Verify register configuration
Check hardware connections
Debug firmware execution
Analyze protocol timing

Refer to Encoder Examples Debug Guide for detailed encoder debugging procedures.

EnDAT3-Specific Debugging

If the EnDAT3 interface is not initializing correctly, follow these steps:

Initialization Failures

Probe the encoder signals:
- Clock (CLK)
- Data Out (TX)
- Data In (RX)
- Transmit Enable (TX_EN)
Capture HELLO command:
- Should see clock at 25 MHz (for 12.5 Mbps mode)
- TX should show Manchester-encoded HELLO command
- RX should show encoder response after ~300ms
Verify timing:
- Preamble: Minimum 25 halfbits
- Command: Manchester encoded
- Postamble: 4 halfbits
Common issues:
- Firmware not loaded to correct PRU core
- Incorrect channel selection
- Encoder not powered or not connected
- Cable delay too large for configured timing

Frame Reception Issues

If frames are received but CRC fails:

Check Manchester decoding:
- Verify LUT values in driver
- Check oversample rate (should be 8x)
- Verify clock alignment
Analyze frame structure:
- HPF: 48-bit data + 8-bit status + 8-bit CRC
- LPH: 8-bit status + 8-bit num_lpf + 16-bit reserved + 8-bit CRC
- LPF: 8-bit status + 48-bit data + 8-bit CRC
Debug with raw data:
- Read RX buffer directly from PRU memory
- Manually decode Manchester encoding
- Calculate expected CRC

Background Communication Issues

If background commands fail:

Check LPH status:
- Must be IDLE (0) or proper state for request
- Cannot send request when BUSY (3)
Verify cycle count:
- Different states require different cycle counts
- Application must handle multi-cycle protocol
Examine LPF responses:
- Check Frame ID (FID) in LPF status byte
- Verify LPF data corresponds to request

Periodic Mode Issues

If periodic mode doesn't trigger:

Verify IEP configuration:
- CMP0 reset count properly set
- For CMP mode: CMPy trigger value properly set and less than CMP0
- For CAP mode: CAPy capture event configured properly
- IEP counter enabled and running
- CMP/CAP events properly configured in SysConfig
- Verify IEP CMP/CAP event status in IEP registers
Check firmware mode:
- Operating mode must be set to 0 (periodic CMP) or 2 (periodic CAP)
- Start trigger must be released
- Command parameters pre-configured
Monitor IRQ generation:
- Firmware should generate interrupt after response
- R5F ISR should be called
- Check INTC configuration
CAP mode specific checks:
- Verify XBAR routing is correct, if routing is needed
- Verify CAP event is detecting the input signal edge

Note: For detailed PRU firmware debugging, connect to the PRU core using CCS and set breakpoints in the firmware code as described in Encoder Examples Debug Guide.

Test Case Summary

The EnDAT3 diagnostic application provides comprehensive UART menu-based test coverage for all protocol features. The test suite covers multiple functional test cases accessible through the interactive UART terminal interface, organized into the following categories:

1. Foreground Communication Tests (15 Test Cases)

Foreground commands are accessed via menu option 0 and provide single-cycle position and control operations:

Basic Position Commands:

DATA0-DATA7 (Menu options 1-8): Activate Low Priority Frame (LPF) send lists 0-7 for retrieving different encoder data sets configured in the encoder
DATA (Menu option 9): General data command with background data support
DATANOP (Menu option 10): Position data request without background data (uses fixed value 0x0000)

Control Commands:

RESET (Menu option 11): Encoder reset functionality with two sub-options:
- Hard Reset (0xBBBB): Full device restart, takes up to 300ms
- Custom Reset: User-defined reset codes for specific reset types
CLEAR (Menu option 12): Reset encoder states (F, W, REF flags) with three selective prompts for flag clearing
ECHO (Menu option 13): Measure propagation time for cable delay compensation with user-defined echo data input
RATE (Menu option 14): Data rate configuration (12.5 Mbps supported; 25 Mbps command available but not functional in current release)
HELLO (Menu option 15): Initialize EnDAT3 communication (uses fixed value 0x2222, takes up to 300ms to establish communication)

2. Background Communication Tests (8 Test Cases)

Background commands are accessed via menu option 1 and require multi-cycle operation based on LPH state machine:

Memory Operations:

NOP (Menu option 1): No operation background command for testing background communication without data transfer
READ (Menu option 2): Read from encoder memory with prompts for:
- Number of words to read
- Address MSB byte (hex)
- Address LSB 2 bytes (hex)
WRITE (Menu option 3): Write to encoder memory (subject to protection levels) with prompts for address and data word
RECONFIGURE (Menu option 4): Reconfigure encoder parameters, causes encoder to enter BUSY state during reconfiguration

Security Operations:

AUTH (Menu option 5): Authenticate with user level and password, with prompts for:
- User level: 0=USER, 1=OEM2, 2=OEM1, 3=MANUFACTURER
- Password (hex, up to 32 bits)
PROTECT (Menu option 6): Set memory protection with three modes:
- QUERY (0x01): Query current read/write access levels for specified address
- SET_READ (0x02): Set read access protection level for address range
- SET_WRITE (0x03): Set write access protection level for address range
SETPASS (Menu option 7): Set password for user authentication levels with prompts for user level and new password
LOCATE (Menu option 8): Encoder location function for physical identification with control value input

3. Continuous Position Fetch Tests (1 Test Case)

Continuous mode is accessed via menu option 2:

Continuous Mode Start/Stop: Non-stop position updates displaying "Position: 0x________, Angle: ___.___ degrees" continuously at ~1000 Hz until Enter key pressed
Position Value Verification: Verify 30-bit position values and angle calculations (360 degrees = 2^30 counts = 1073741824) while rotating encoder

4. Periodic Trigger Mode Tests (2 Test Cases with Multiple Scenarios)

Periodic mode is accessed via menu option 3 or 4 with mode selection (CMP or CAP) and IEP timer configuration:

CMP/CAP Mode Tests:

Invalid Configuration Handling: Test periodic_trigger_count > iep_reset_count validation
Normal Frequency Operation: Test periodic updates at configurable rates (e.g., 5 Hz with iep_reset_count=40000000, periodic_trigger_count=10000000 at 200 MHz IEP clock)
High Frequency Operation: Test 1 kHz position updates (iep_reset_count=200000, periodic_trigger_count=10000) for real-time performance validation

Note: Arm is a registered trademark of Arm Limited (or its subsidiaries or affiliates) in the US and/or elsewhere.

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