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.

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 CFI_MAC_DEF and CFI_MAC_ENDEF. The default macros are shown in the following table.

Commands

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

CFI_CHE_PEEK - Read CHEAP Hardware

Read a 16-bit data value from the CHEAP hardware and telemeter the result. Note: only one peek or poke can be commanded per second.

CFI_CHE_POKE - Write CHEAP Hardware

Write an 8-bit data value to the CHEAP hardware. Note: only one peek or poke can be commanded per second.

CFI_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 actuator power is removed automatically by the DPU software once the cover is open. 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 CFI_COV_MODE command. Note: the imager primary power must be turned on for the cover to deploy.

CFI_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 CFI_COV_DEPLOY).

CFI_DOS_DATA - Collect Dosimeter Data for Downlink

Collect dosimeter data and downlink it.

CFI_DUS_DATA - Collect Dust Shield Data for Downlink

Collect dust shield data and downlink it.

CFI_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.

CFI_FLT_PWR - Control Filter Wheel Power

CFI_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.

CFI_HTR_MODE - Set Heater Control Mode

Select heater off, on, or controlled by software.

CFI_HTR_SENSOR - Select Heater Control Sensor

Select the temperature sensor used to control the heater.

CFI_HTR_TMP - Set Heater Temperature

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

CFI_IMG_COMP_ALG - Select Image Compression Algorithm

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

CFI_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.

CFI_IMG_EXP - Set Image Exposure Time

Set image exposure time. An exposure time set at time t effects the exposure taken at t+1. The exposure time is specified in two pieces. The first argument how long to expose in the first second; this can range from 2.048 ms to 958.464 ms. The second argument specifies additional whole seconds of exposure. Note: If the commanded exposure time is greater than the commanded collection interval (see CFI_IMG_IMAGE), the exposure time is reduced to match the collection interval.

CFI_IMG_FORMAT - Select Image Format

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

CFI_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 CFI_IMG_IMAGE is issued, the new command supersedes the old command.

CFI_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.

CFI_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.

CFI_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.

CFI_MEM_STR_READ - Read a Data Structure

Dump the identified data structure.

CFI_MIR_MOVE - Move Cube Mirror

Move cube mirror to use the indicated side. Note: the CM motor primary power must be turned on for the cube mirror to move.

CFI_MIR_PWR - Control Mirror Power

Turn cube mirror resolver power off or on. Note: the CM motor primary power must be turned on for the cube mirror resolver to operate.

CFI_MIR_STEP - Step Cube Mirror

Move cube mirror the indicated number of resolver counts. Note: the CM motor primary power must be turned on for the cube mirror to move.

CFI_PWR_PRI - Control Primary Power

Turn primary power off or on to a selected subsystem.

CFI_SAD_EXP - Set DSAD Image Exposure Time

Set DSAD image exposure time.

CFI_SAD_IMAGE - Collect DSAD Data for Downlink

Take a DSAD image, collect data, and downlink it. Summary data is collected from the indicated DSAD and telemetered. If requested, the associated raw image is also sent

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