Command Interface

The DPU receives and processes CCSDS telecommand packets containing one or more commands. The format of the telecommand packet and constituent commands is described in Reference 3.

Command and Macro Processing

Most commands are executed as soon as they are received; exceptions are noted in the individual command descriptions. Each command is echoed after it is executed by the DPU. A command echo subpacket containing the opcode and some arguments along with a code summarizing the command's result is downlinked. Most TPU commands are not executed by the DPU but are forwarded to the TPU. The DPU echoes the command after it has been executed by the TPU.

Some default macros are available as soon as the DPU is started. Most of these macros are one or two commands long and are used by the monitoring subsystem to respond to out of limit conditions. A default macro can be replaced with a new macro via CRS_MAC_DEF and CRS_MAC_ENDEF. The default macros are shown in the following table.

Commands

The CRISP and CFI common commands are described in Reference 3. CRISP-specific commands are defined below.

CRS_CA_RESET - Reset Closest Approach

Reset closest approach processing logic.

CRS_CA_START - Start Closest Approach

Start closest approach processing logic. Also, enable or disable selection of backup closest approach macro.

CRS_COV_DEPLOY - Deploy the Cover

Turn power to cover's HOP actuators off or on. Turning on the actuator deploys the cover. With operation 2, the power is removed automatically from all of the actuators by the DPU software ten seconds after the cover is open; "open" is defined as either HOP telltale indicating "extended". With operation 3, the actuator power is removed after a timeout period; the timeout is a parameter. With operation 4, the actuator power is removed once the cover is open or the timeout period elapses. This command will be rejected unless specifically enabled with the CRS_COV_MODE command. Note: the imager primary power must be turned on for the cover to deploy.

CRS_COV_LED - Control Cover LED Power

Turn cover's telltale LED power off or on. Note: the imager primary power must be turned on for the LEDs to light.

CRS_COV_MODE - Enable/Disable Cover Deployment

Enable or disable deployment of the cover. This is a safety interlock; the actuators must be enabled before actually powering the actuator (with CRS_COV_DEPLOY ).

CRS_FLT_MOVE - Move Filter Wheel

Move filter wheel to indicated position. The filter movement begins at the end of the current exposure. Note: the FW motor primary power must be turned on for the filter wheel to move.

CRS_FLT_PWR - Control Filter Wheel Power

Turn filter wheel resolver power off or on. Note: the FW motor primary power must be turned on for the filter wheel resolver to operate.

CRS_FLT_STEP - Step Filter Wheel

Move filter wheel the indicated number of resolver counts. Note: the FW motor primary power must be turned on for the filter wheel to move.

CRS_HTR_MODE - Set Heater Control Mode

Select heater off, on, or controlled by software.

CRS_HTR_TMP - Set Heater Temperature

Set temperature goal of the heater in the indicated zone. The temperature will be held between the given setpoint and setpoint+hysteresis.

CRS_IMG_COMP_ALG - Select Image Compression Algorithm

Select image compression algorithm. When executed at time t affects the exposure taken at time t+1.

CRS_IMG_COMP_MODE - Enable/Disable Image Compression

Enable or disable image compression. When executed at time t affects the exposure taken at time t+1.

CRS_IMG_EXP - Set Image Exposure Time

Set image exposure time. An exposure time set at time t effects the exposure taken at t+1. Exposure times can range from 128 µs to 979.968 ms.

CRS_IMG_FORMAT - Select Image Format

Select the format of the images to be telemetered. When executed at time t affects the exposure taken at time t+1.

CRS_IMG_IMAGE - Collect Images for Downlink

Collect a series of images and downlink them. An exposure requested at time t is taken at t+1. If an image collection series is in progress and a new CRS_IMG_IMAGE is issued, the new command supersedes the old command.

CRS_IMG_PWR - Control Imager Power

Turn imager FPU power off or on. Note: the imager primary power must be turned on for the imager FPU to activate.

CRS_IMG_REGION - Select Image Region of Interest

Set the origin of the image to be telemetered. When executed at time t affects the exposure taken at time t+1.

CRS_IMG_TRACK - Collect Tracking Images

Collect a series of images for the TPU. An exposure requested at time t is taken at t+1. If an image collection series is in progress and a new CRS_IMG_TRACK is issued, the new command supersedes the old command.

CRS_MEM_STR_LOAD - Load Values into a Data Structure

Load the data values into the identified data structure at the location denoted by the offset. The byte count determines how many load bytes follow and may be up to 128 bytes. The padding after the data forces the size of the load to be a multiple of 4 bytes; M+N is always a multiple of 4.

CRS_MEM_STR_READ - Read a Data Structure

Dump the identified data structure.

CRS_PWR_PRI - Control Primary Power

Turn primary power off or on to a selected subsystem.

CRS_SPC_CAL_LEVEL - Set Spectrometer Calibrator Level

Set the level, and consequently the brightness, of the spectrometer's IR calibration lamps.

CRS_SPC_CAL_PWR - Control Spectrometer Calibrator Power

Calibrate spectrometer by turning two IR calibration lamps off or on.

CRS_SPC_COOL - Control Spectrometer Cooler Power

Turn spectrometer cooler power off or on. There are two possible temperatures to select when the cooler is on. Note: the spectrometer primary power must be turned on for the cooler to operate.

CRS_SPC_FORMAT - Select Spectrometer Image Format

Select the format of the spectrometer images to be telemetered.

CRS_SPC_PWR - Control Spectrometer Power

Turn spectrometer FPU power off or on. Note: the spectrometer primary power must be turned on for the spectrometer FPU to operate.

CRS_SPC_RANGE - Select Spectrometer Image Range

Select a range of bits within each spectrometer pixel; these are the bits that will be telemetered.

CRS_SPC_RATE - Control Spectrometer Collection Rate

Control the spectrometer collection rate. Note: even if no spectra are being telemetered, the spectrometer will be cycled at this rate.

CRS_SPC_REGION - Select Spectrometer Image Region of Interest

Set the origin of the spectrometer image to be telemetered.

CRS_SPC_SPECTRA - Collect Spectra

Collect spectra. The collection will occur for the indicated time; a special value will produce continuous collection. A request for spectra made at time t starts at t+1. The number of spectra actually taken depends on the commanded spectrometer rate (CRS_SPC_RATE).

CRS_SPC_TMP - Enable/Disable Spectrometer Temperature Monitoring

Enable or disable temperature monitoring in the spectrometer front end.

CRS_TPU_AIM_ALG - Select Aim Algorithm

Select the aim algorithm used by TPU image processing to find the comet.

CRS_TPU_ATT_RESET - Reset Attitude Algorithm

Reset the TPU's attitude estimation algorithm.

CRS_TPU_IMG_REGION - Select Tracking Image Region of Interest

Set the origin of the region interest in the tracking image.

CRS_TPU_IMG_ZOOM - Select Tracking Image Zoom

Set the zoom mode of the tracking image.

CRS_TPU_MEM_CHECK - Check TPU Memory

Calculate the checksum of TPU memory at given address. The checksum is the 32-bit two's complement sum of the memory indicated. The results are downlinked in a subpacket.

CRS_TPU_MEM_COPY - Copy TPU Memory

Copy TPU memory from source to destination. The source or destination can be either RAM or EEPROM. The result is undefined if the source and destination regions overlap.

CRS_TPU_MEM_LOAD - Load TPU Memory

Load memory to the TPU. The byte count determines how many load bytes follow and may be up to 128 bytes. The padding after the data forces the size of the load to be a multiple of 4 bytes; M+N is always a multiple of 4.

CRS_TPU_MEM_READ - Read TPU Memory

Dump TPU memory from given address.

CRS_TPU_MEM_READ_ABT - Abort TPU Memory Read

Abort the current TPU memory dump.

CRS_TPU_MEM_RUN - Run a TPU Program

Run a program at the given TPU address. The program must either execute very quickly (so as not to hold up the command handler) or must take over completely.

CRS_TPU_MEM_STR_LOAD - Load Values into TPU Data Structure

Load the data values into the identified data structure at the location denoted by the offset. The byte count determines how many load bytes follow and may be up to 128 bytes. The padding after the data forces the size of the load to be a multiple of 4 bytes; M+N is always a multiple of 4.

CRS_TPU_MEM_STR_READ - Read TPU Data Structure

Dump the identified data structure.

CRS_TPU_MIR_ANGLE - Set the Slew Mode Target Angle

Sets the angle of the target to use when in slew mode (see CRS_TPU_MIR_MODE). The angle specifies the imager's look direction; a zero angle looks along the nose of the instrument. Note that this is not the same as the mirror shaft angle. The actual mirror shaft angle used will depend on the commanded angle and mirror side (see CRS_TPU_MIR_SIDE).

CRS_TPU_MIR_HOME - Find Mirror Home Position

Search for mirror home fiducial. Once found, move the mirror to 90 degrees, and set the mirror mode to "hold".

CRS_TPU_MIR_MODE - Set the Mirror Mode

Sets the control mode of the tracking mirror. When off, the mirror motor is not driven. In hold mode, the mirror is held at the current position. In slew mode, the mirror is held at a commanded angle (see CRS_TPU_MIR_ANGLE). In scan mode, the mirror follows a profile computed by the tracker. Whenever the mirror mode is commanded, the mirror controller is reset.

CRS_TPU_MIR_PWR - Control Mirror Motor Power

Turn mirror motor power off or on. Turning off the motor power also sets the mirror control mode to "off" (see CRS_TPU_MIR_MODE).

CRS_TPU_MIR_SIDE - Select Mirror Side

Selects which side of the mirror to use.

CRS_TPU_OFF_ANGLE - Set the Target Offset Angle

Set the target offset angle. If automatic offset adjustment is enabled (see CRS_TPU_OFF_MODE), the angle will be modified at a commandable rate (see CRS_TPU_OFF_RATE). Note that the angle corresponds to the line-of-sight target angle rather than the mirror shaft angle.

CRS_TPU_OFF_MODE - Enable/Disable Automatic Offset Adjustment

Enable or disable automatic offset adjustment. When enabled the offset is adjusted based on the last commanded initial angle (CRS_TPU_OFF_ANGLE) and the rate (CRS_TPU_OFF_RATE). When disabled, the offset is held at the last computed offset; when re-enabled, the offset adjust will pick up where it left off. While disabled, the offset can be commanded to a fixed position via CRS_TPU_OFF_ANGLE).

CRS_TPU_OFF_RATE - Set the Automatic Offset Rate

Set the automatic offset rate. The mirror is adjusted by the commanded rate. This rate is only used when automatic offset adjustment is commanded (CRS_TPU_OFF_MODE). Note that this rate applies to the line-of-sight target angle and not the mirror shaft angle.

CRS_TPU_TEST - Enable/Disable Test Mode

Enable or disable test mode. In test mode, the tracking image is loaded from a test port rather the FPU. This is only useful during testing on the ground.

CRS_TPU_TLM_FLUSH - Flush TPU Telemetry Subpackets

If there is a partially filled subpacket packet in the TPU, generate a flush subpacket so that the packet will be downlinked.

CRS_TPU_TLM_FLUSH_AUTO - Enable/Disable Automatic Flush

Enable or disable automatic flushing of partially filled subpacket packets in the TPU. If enabled, the TPU will try to send a subpacket packet every other second, even if the packet has not been completely filled. This is most useful during ground testing since it gives a low-latency response.

CRS_TPU_TRK_ALG - Select Tracking Algorithm

Select tracking algorithm.

CRS_TPU_TRK_GOAL - Set Tracker Goal

Set desired target position on CCD. The tracker tries to place the target at the specified position.

CRS_TPU_TRK_LOOP - Enable/Disable Closed-Loop Tracking

Enable or disable closed-loop tracking.

CRS_TPU_TRK_TLM - Enable/Disable Tracking Telemetry

Enable or disable tracking telemetry production.

Return to CRISP Software User's Guide. Report problems to John Hayes.