Microbrain Intelligent Technology CAR-N28 User manual

CAR-N28
User manual of CAR-N28 Medium/Short Range Radar
2019.07.30
长沙莫之比智能科技有限公司
Microbrain Intelligent Technology Co., Ltd.

1.Introduction
The CAR-N28 is a medium&short range millimeter wave radar developed by
MBIT for applications such as vehicle blind spot detection (BSD),front and rear
parking assistance. The radar works at the frequency band which covers from
79GHz to 81GHz. The detected object information could be transferred to the
host via CAN interface. The transmitter and receiver adopts MIMO array
antenna which enables the radar high angle resolution and angle
measurement accuracy. The signal processing and control unit ultilizes
DSP+ARM dual-core architecture which provides best performance for the
online processing algorithms such as radar data processing, target detection
and target tracking.
Higlights of CAR-N28 radar:
1. Time duplexed medium range or short range working mode or just work
either this two mode according to the desired range of specified user
application;
2. Onboard detected target information supports CAN output, and specified
alarm strategies are available for secondary development by customers;
3. A 2Tx4Rx MIMO array antenna is designed to ensure high Angle resolution
and angular measurement accuracy;
4. DSP+ARM dual-core architecture is integrated for signal processing and
control unit.
Product Performance Specification
Characteristic
Parameter Name
Specification
System properties
Working voltage
8-36V
Operating temperature
-40°C~85°C
Power consumption
< 2W
Water resistence level
IP67
Carrier Frequency
77-81G
Frame rate
20Hz

Communication interface
CAN
Shell size
66*66*22.9mm
Weight
132.4g
Antenna performance
Number of transceiver
channels
2TX4RX
Elevation scope
-10~10degree
Azimuth scope
-60~60degree
Short range detection
performance
Range resolution
0.04m
Velocity resolution
0.1m/s
Velocity Scope
-30km/h~30km/h
range accuracy
<0.02m
Velocity accuracy
0.1m/s
Rngular accuracy
better than 0.1°
Range scope
0.1m~20m
Upgrade or
debugging
Rirmware upgrade
via CAN2.0 Interface
Data calibration
via CAN2.0 Interface
Medium range
detection
performance
Range resolution
0.36m
Velocity resolution
0.25m/s
Velocity range
-90km/h~90km/h
Range accuracy
<0.18m
Velocity accuracy
0.1m/s
Angular accuracy
better than 0.1°
Range scope
0.5 - 80m
Upgrade or
debugging
Firmware upgrade
via CAN2.0 Interface
Data calibration
via CAN2.0 Interface
2.Product Highlights
CAN interface included: CAN bus communication network conforms to
ISO1188-2 standard is included. The default frame type is standard frame
and the default Baud rate is 500K.
Medium and short range working mode in one device: The CAR-N28
radar could work in either medium range mode or short range mode. The
maximum range for typical vehicle detection in medium range mode could
reach 80 meters while the range would be 20meters with better range
resolution in short range mode.
Multiple type output specification: There are five types of target
information that could be set by customers. In medium range mode the
output could be the points cloud and target tracks information. While in
short range mode, the output information could be points cloud , clustering
cloud and target tracks.

Radar ID configuration function: There could be a maximum of 16
devices mounted on just one CAN bus with each device its own ID
assigned. The default radar ID is set to 0. CAR-N28 Radar message ID
calculation method: Radar message ID = radar ID * 0x10 + ID of base
message .
Configuration persistance: When host computer software resets the
radar parameters, the previous configuration will be restored if the power is
cut off and the radar is restarted before saving operation.
Note:
The above configuration functions could be configured by host computer
software, or set by sending specific CAN command. Please refer to the
detailed subsection 6 as below.
3. Installation Instructions
Installation Orientation:
The antenna surface of the radar module (flat surface) is facing to the
detection area, with the heat sink facing up, and the angle could be slightly
adjust vertically and horizontally. And the connector should go out to the right.
Figure 1 Schematic diagram of radar installation direction
Installation location:
It is recommended to install the radar the downside of the front bumper bar
and keep it from 0.5 meter to 1.0 meter above the ground. If the available
installation height is less than 0.5 meter, the installation pitch angle should be
adjusted appropriately.

Note:
1. Looking forward from the back, the left side of the radar is the negative axis
of X-axis, the right side is the positive axis of X-axis;the front side of the radar
is the positive axis of Y-axis, and the far away from the radar is the positive
velocity, while close to the radar is the negative velocity.
2. Cartesian coordinate system is used for point cloud, target track and
clustering cloud, and polar coordinates are used for tracking output.
4.Description Of Interface Cable
The CAR-N28 radar adopts 6 PIN connector, and its shape and structure are
shown in the figure 2:
Figure 2 Connector structure drawing
Stitch definitions are shown in the table 8：
Table 8 Stitch definitions
pin
Cable identification
Cable color
Description
1
GND
black
negative pole of Power
2
VCC
red
positive pole of Power
3
UART RX
green
Serial TTL 3.3V level RX/
CAN2_L
4
CAN-L
yellow
CAN1-L
5
UART TX
white
Serial TTL 3.3V level TX/
CAN2_H
6
CAN-H
blue
CAN1-H
Note: The serial interface of Pins 3 and Pin 5 is only used for internal
debugging.

5.CAN Interface Protocol
(1) The frame type is standard frame.
(2) The default Baud rate is 500K.
(3) Radar configuration ID = 0x201, radar Reply ID = 0x202.
6. ConfigureThe Radar ID
(1) The specified Radar ID could be set through the host computer software.
Figure3 Radar ID setting GUI
(2) Configure the command format through CAN command:
Table 9 CAN command format for Radar ID setting
Signal
start bit
length(bit)
value
definition
Data Type
0
7
1
1：Radar ID
R/W
7
1
-
0: Read; 1: write
Value
8
8
-
Radar ID
Read the radar ID: Data Type = 1, R/W =0, Value =0x00;
Write the radar ID: Data Type = 1, R/W = 1, Value = radar ID .
7. Medium/Short Range Mode Setting
(1) The medium or short range mode could be set through the host computer
software.
Figur4 Radar range mode setting GUI
(3) Configure the command format through CAN command:
Table 10 CAN command format for Radar Range Mode setting
Signal
Start
Length
Value
Definition

bit
(bit)
R/W
7
1
-
0: Invalid; 1: write
Radar_Mode
8
2
0
1: Short distance; 2: long distance
This command is a write-only command. e.g. if need set the short distance
mode ,you should sends: 0x85 0x01.
8.Output Information Format Defining
(1) The Output Information Format could be defined through the host computer
software.
Figure5 Radar Output Information Format setting GUI
(2) Configure the command format through CAN command:
Table 11 CAN command format for Radar Output Information Format
Signal
Start bit
Length(bit)
Value
Definition
DataType
0
7
3
3：Target output
selection
R/W
7
1
1
0: Invalid;1: write
PointOutput
8
1
-
Point cloud information
output0 ：Disable ；1：
enable
ClusterOutput
9
1
-
Clustering information
output0：Disable；1：
enable
TraceOutput
10
1
-
Trace information
output0：Disable；1：
enable
IIRFilterOutput
11
1
-
IIR filter information
output0：Disable；1：
enable
Reserve
12
4
-
default :0

This command is a write-only command. e.g. If need to set the short distance
mode ,you should to send: 0x85 0x01 string via CAN.
(3)All the configuration could be save by click the ‘Save setting’ button on the
host computer software.
Figure6 Configuration saving GUI
(4) Configure the command format through CAN command:
Table 12 CAN command format for Radar Configuration Saving
Signal
start bit
length(bit)
value
definition
Data
Type
0
7
7F
7F：Save the parameters
R/W
7
1
1
0: Invalid;1: write
Value
8
8
0
Value = 0x00
This command is a write-only command and requires two bytes to be sent, with
the second byte sending 0x00 string by default.
9.Attention
Please read the instructions carefully before use
1. Make sure the power supply is stable to get best radar detection
performance.
2. Don’t impact or drop the radar to the groud in case of product damage.
3. The radar antenna is integrated inside. If there is any attachments on

surface of the radar such as water droplets, rain, snow, dust, etc., it should be
cleaned in time.
4. the USBCAN box which supports USBCAN(Canalyst-II) and the driver
should be prepared for the radar debug and online testing. The CAN box as
shown in the figure 25 should be used to communicate with the CAR-B51.The
shipping list does not contain USBCAN boxes by default, customers could find
the CAN box link address from Customer Service of Micro Brain Intelligent
Technology Co. Ltd. to purchase the device online.
Figure7 USBCAN box
5. Failed to receive data during testing? Just following the below diagnose
steps:
Check whether the USBCAN box is suitable.
Check whether the power supply is connected correctly (12V).
Check whether the terminal resistance switch of the USBCAN box is
on.