UM-003 OPS243-A User Manual OmniPreSense OPS243-A short range radar sensor has an easy to use API to control the output of the sensor. Simple commands can be used to configure the operation and output information provided by the sensor. Default settings are noted below. Upon powering on the module, the default settings are used. Installation Instructions The OPS243-A provides a complete radar module on a single board.
Radar Sensor Types OmniPreSense provides two different types of sensors, Doppler radar sensor reporting motion and speed and FMCW radar sensors reporting range. The feature differences for these sensors is shown in Table 1. The following API commands pertain to both types of sensors except for special cases. In these cases, this document will call out the special command for either a Doppler (-A), FMCW (-B), or both Doppler and FMCW (-C) radar. Table 1.
Figure 3. PuTTY Startup Menu Once connected, the data reported by the sensor will start streaming to the terminal when an object either in motion appears (-A, -C Doppler radar sensors) or there are objects in the sensors field of view (B, -C FMCW radar) to report the range to. The default settings are shown in Table 2. If there is no object moving in front of the sensor or it’s not pointing at any object, no data is reported or streamed to the terminal.
Figure 5.
Default Settings The default settings of the module are set to provide solid performance over a wide range of applications. Upon power-up the default settings are used, and operation begins. Future updates will allow the module to retain the settings of the module from the last operation. The default settings are listed in Table 2. Table 2.
Table 3. Maximum Operating Speeds Sample Frequency 1,000 5,000 10,000 20,000 50,000 100,000 API Command SI SV SX S2 SL SC Maximum Speed (m/s) 3.1 15.5 31.1 62.2 155.4 310.8 Maximum Speed (mph) 7.0 34.8 69.5 139.1 347.7 695.4 Resolution* Resolution* (m/s) (mph) 0.006 0.014 0.030 0.068 0.061 0.136 0.121 0.272 0.304 0.679 0.608 1.
API Commands The following are the API commands supported by the OPS243. These commands can be sent by typing into the command terminal to change settings on the sensor or control its operation. The commands provided include simple queries to fetch information about the sensor and its settings or write commands which control or change the operation of the sensor. Module Information – returns information about the module and its setting.
Speed Output Units (-A, -C Doppler only) – read or set the units for the velocity output. Units supported include m/s (default), cm/s, ft/s, km/hr, and miles per hour.
Sampling Rate/Buffer Size (-A, -C Doppler only) – set these values to control the sample rate of the module. This setting influences the output data and the rate at which the data is reported. The buffer size influences the report rate and resolution. A buffer size of 512 will have a report rate between 5-30Hz. The resolution becomes worse by a factor of two with a 512-buffer size versus 1024 (Figure 6) and worse again at 256 buffer size.
Reported Speed/Range/Direction Filter – use these settings to set the range of data to report. Settings are available for either a minimum or maximum value below or above which data will not be reported. Commands are available to set speed, range, and direction of speed filters. These filters can be used to help set sensitivity levels of detection. This command requires a return () after the number. Direction filter allows reporting only a single direction or both.
Data Output – set to control the data output. Command Name R/W OD Range Report Write OS Speed Report Write OF FFT Output On Write OG Object Sensor Light Write OC Processing Light Activity Write OJ JSON Mode On Write UM-003-A OPS243-A User Manual 11 Value Turn range reporting on or off. Default operation range is reported. Use Od to turn it off and OD to turn it back on. FMCW (-B, -C) radar only. Turn speed reporting on or off. Default operation speed is reported.
Command Name R/W OR Raw ADC Output On Write OL LED Control Write OM Magnitude Report Write On Number of Reports Write OT Time Report Write OU Units Report Write OV Range Report Order Write BZ BL BS BC BT BV Blank Data Reporting Write UM-003-A OPS243-A User Manual 12 Value I and Q output buffers from the ADC will be sent. Data output will alternate between the I and then Q buffer. Or turns off raw ADC reporting.
UART Control – set to control the UART interface. The default configuration is 8-bits, no parity, 19,200 baud rate, and 1 stop bit. The OPS243 will start reporting out on the UART immediately after power on. If the USB is enumerated, the UART reporting will be shut off and data will be reported out USB. It’s not recommended to use OF with UART, especially at low baud rates. Command I? In Name Query Baud Rate R/W Read Baud Rate Write Value Outputs current baud rate and oversampling setting.
Simple Counter – counts objects which meet the speed/range and signal magnitude filtering settings. The counter will count the number of objects over time which meet the filtering settings for speed/range and signal magnitude. The count is not reported but can be queried with the N? command. The count can be reset with the N! command. A count is triggered if 2 or more consecutive reports meet the threshold limits.
Module/Transmit Power – set to control the operating mode (PA, PI, PP) or the transmit power. The typical maximum transmit power is 9 dB. Reducing the transmit power does not reduce the overall power consumption of the module. Note that the detection range will decrease with decreased transmit power.
Short Duty Cycle Control – set to control duty cycle operation under 1 second. The time set is the amount of time the sensor will delay between outputting the last report and starting the next report.
Magnitude Control – provides control over the sensitivity of the module to detect moving objects. Low numbers are most sensitive, high numbers are least sensitive. Magnitude is related to Squelch as the square root of the number. For example, a magnitude setting of 10 is equal to a Squelch setting of 100 (QI). Command M? m? M>n Name Current speed magnitude setting Current range magnitude setting Low Speed Magnitude Filter R/W Read Value Doppler (-A, -C) radar only. Read FMCW (-B, -C) radar only.
Persistent Memory – saves current configuration into flash memory and is retained even if power is removed. Command A! Name Save Configuration R/W Write A. AX Read Settings Reset Flash Settings Write Write UM-003-A OPS243-A User Manual 18 Value Saves current configuration settings in flash memory. Upon power loss or recycling power, the saved configurations will be used as the default. Read the current flash settings. Will overwrite current saved settings and return to the factory default settings.
FCC 15B Statement This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications.
Non-modification Statement OmniPreSense Corporation has not approved any changes or modifications to this device by the user. The antenna design is intended to be used as is with no modifications. Any changes or modifications could void the user’s authority to operate the equipment.
Appendix Table 4. OPS243 Code Version Matrix Feature V1.0.
Revision History Version A Date November 14, 2019 Description Initial release.
