CRG20

A low-cost miniature gyro, optimised for medium volume production programmes where high stability, performance and cost are key drivers. Available in  a variety of rate ranges - +/-75°/s and +/-300°/s, plus a new high rate range (800°/s) variant. Digital (SPI®) and analogue outputs. Low drift and excellent performance over temperature

The CRG20 gyro is a fully integrated digital solution, comprising MEMS sensing element, digital acquisition ASIC, and microprocessor. This single chip solution minimises the requirements for additional electronics, and thereby reduces space requirements and overall system costs. Fully digital closed loop control eliminates any temperature and ageing effects associated with analogue electronics, and provides exceptionally stable performance over a wide range of operating conditions.

In addition to a commanded self test feature, CRG20 incorporates continuous self-testing of the complete operation of the sensor and the signal conditioning circuits. CRG20 has been designed to provide unparalleled sensor integrity, through the mitigation of potential error sources and false-plausible failure modes. System designers have the opportunity with CRG20 to eliminate the requirement for redundant sensors in high integrity applications.

The sensor provides a digital interface in the form of a SPI® port together with analogue output pins for customers who need to operate in the analogue domain. In addition, two auxiliary analogue input pins are available to digitise other sensors such as accelerometers or additional gyros; this enables multi-axis sensor clusters to be easily produced.

Product Lifecycle Status

Production Status: In Production

Availability: Available
Customer Applications: New and existing applications

Find out more about product lifecycle status

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Supply Voltage (Vdd)

Digital Dynamic Range

Analogue Dynamic Range

SF Setting Error

SF Error Over Temp

Bias Setting Error

Bias over Temperature

Bias Repeatability

Bias Instability

Bandwidth (nominal)

Operating Temperature

CRG20-01

5.0V

±300°/sec

±75°/sec

±0.5%

±2.0%

±0.5°/s

±2.5 ̊/sec

±0.07 ̊/s (1σ)

5°/hr

40Hz

-40°C to +105°C

Under $ Qty
Unit Price
1 - 9
$161.09
10 - 24
$161.09
25 - 49
$161.09
50 - 99
$Enquire
Download Data Sheet

CRG20-02

5.0V

±300 °/sec

±300 °/sec

±0.5%

±2.0%

±0.5°/s

±2.5 ̊/sec

±0.07 ̊/s (1σ)

5°/hr

75Hz

-40°C to +105°C

Under $ Qty
Unit Price
1 - 9
$161.09
10 - 24
$161.09
25 - 49
$161.09
50 - 99
$Enquire
Download Data Sheet

CRG20-22

5.0V

±300 °/sec

±300 °/sec

±0.5%

±2.0%

±0.5°/s

±2.5 ̊/sec

±0.07 ̊/s (1σ)

5°/hr

90Hz

-40°C to +105°C

Under $ Qty
Unit Price
1 - 9
$161.09
10 - 24
$161.09
25 - 49
$161.09
50 - 99
$Enquire
Download Data Sheet

CRG20-12

5.0V

±800°/s

±800°/s

±0.5%(Dig)

±2.5%

±0.5°/s

±2.5 ̊/sec

±0.07 ̊/s (1σ)

-

40Hz

-40°C to +105°C

Under $ Qty
Unit Price
1 - 9
$161.09
10 - 24
$161.09
25 - 49
$161.09
50 - 99
$Enquire
Download Data Sheet

Supply Voltage (Vdd)

Digital Dynamic Range

Analogue Dynamic Range

SF Setting Error

SF Error Over Temp

Bias Setting Error

Bias over Temperature

Bias Repeatability

Bias Instability

Bandwidth (nominal)

Operating Temperature


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FAQs

  • CRG20
    • What is the logic level for the CRG20's RESET_IN line?

      The reset line is connected directly to a 3.3V device within the gyro (which is also 5V tolerant).  It is triggered at 0.7*3.3V = 2.31V.

      How can I get started working with the SPI interface?

      Use a SPI to Serial converter to interface between a PC and the CRG20.  The one we have used  has an Atmel AT90S8535 microcontroller on it and the SPCR register is set up with 0x51.

      Below is the code we use to transfer a message to and from the CRG20, another piece of code sends the message out to the PC via a serial port which also receives any messages for the CRG20:

      #include  <io8535.h>
      #include  <stdio.h>
      #include  "defines.h"
      #include  "types.h"
      #include  "prototypes.h"
       /*---------*/
      /* Globals  */
      /*---------*/
      extern unsigned char Latest_Tx_SPI_Message[NO_OF_BYTES_IN_SPI_MESSAGE];
      extern unsigned char Latest_Rx_SPI_Message[NO_OF_BYTES_IN_SPI_MESSAGE];
      /*----------------*/
      /*  Initialise_SPI */
      /*----------------*/
      void  Initialise_SPI_As_Master()
      {
        /* Set data  direction register for port B (SPI port) to make  */
        /* SCK  an  output                                             */
        /* MOSI an  output                                             */
        /* MISO an  input                                              */
        /* SS   an  output                                             */
        /* The  register initialises to all 0 so everything else is an */
        /* input, I know | 0<< does  nothing but it makes the point as */
        /* this bit should be 0.                                       */
        DDRB =  (1<<DDB7) | (0<<DDB6) | (1<<DDB5) |  (1<<DDB4);
        /* Drive the  SS line high to stop any chance of the SPI port  */
        /* being deselected                                            */
        PORTB = PORTB  | (1<<PB4);
        /* Enable SPI  in Master mode and set clock to be fck/16       */
        /* This should give a SPI bus clock of 3.69MHz/16 = 230.625KHz */
        SPCR =  (1<<SPE) | (1<<MSTR) | (0<<SPR1)|  (1<<SPR0);
      }
      /*-----------------------------------*/
      /*  Transfer_1_Message_Using_SPI_Port */
      /*-----------------------------------*/
      void  Transfer_1_Message_Using_SPI_Port()
      {
        int  i;
        /* Set SS  line low */
        PORTD = PORTD  & ~(1<<PD2);
        /* Add delay  to allow Mega88 to complete a host message update  */
        Timer_2_Delay_5uS();
      for(i=0;  i<NO_OF_BYTES_IN_SPI_MESSAGE; i++)
        {
          /* Get a byte from the buffer and place it in SPI output register */
          SPDR =  Latest_Tx_SPI_Message[i];
          /* Wait for  the data to be sent */
          while(  (SPSR & (1<<SPIF)) != (1<<SPIF) );
          /* Copy the  received byte into the buffer */
          Latest_Rx_SPI_Message[i] = SPDR;
          /* N.B. For  faster CPU’s place a delay in here */
      
        } 
      
        /* Set SS  line high */
        PORTD = PORTD  | (1<<PD2);
      }

       

      Please note that this controller is working at 3.69MHz (considerably slower than the CRG20 processor) so the time it takes to check the data has been sent and copy in the received byte is equivalent to the delay needed between bytes. If a faster processor was used we would have to add a delay

      What are the switching levels for the SPI lines?

      The input switching level for the SPI (and CBIT) high  input pins is 0.6 * VDD.  At 5V VDD this = 3.0V

      The input switching level for the SPI (and CBIT) low input pins is 0.3 * VDD.  At 5V VDD this = 1.5V

      There is an unexpected 10deg/s offset at the CRG20 output

      It is possible that this is the result of an unintentional activation of Commanded BIT.  Triggering CBITA results in a rate offset of around 10-13 deg/s being applied to the sensor output (either from the SPI digital interface or either of the analogue outputs).  For this reason it is recommended that the CBITA line is pulled low if is not being used (see note 3 in CRG20-00-0100-0110 rev 9 specification).

      Is CRG20 sensitive to linear acceleration?

      Our devices are inherently insensitive to linear acceleration or g. The vibrating structure is a ring and is made to resonate at about 14 KHz. If the ring moves under acceleration load, the modulation and de-modulation signals and the amplitudes are not affected. Therefore we expect very little g sensitivity. When the design requirements were formulated for CRG20, the design requirement was set at 0.1 deg/s/g. Our design verification tests have confirmed very little g sensitivity at all accelerations above 4g (typically <0.0001 deg/s/g). Measurements below 4g are dominated by other error sources such as bias instability and bias and SF changes with temperature and therefore it is difficult to attribute which errors are due to g sensitivity. So when we do a g sensitivity test, we assume that all measurement errors are due to g sensitivity and this results in a very pessimistic number. Our experience is therefore that it is not necessary to compensate for g sensitivity. If you wish to confirm this for yourselves, you could try a simple +/- 1g tumble test, and average the data for about 30 seconds, to see if there are any measurable changes when the g changes from +1g to -1g. Earth rate may need to be allowed for too.

      CRG20 runs from a 5V supply but I would like to interface it to a 3.3V system. What is the voltage range on the SPI IO pins. Can it support a 3.3V interface?

      The CRG20 needs to be powered from a 5V supply. To interface it to a 3.3V system will require a special attention to the logic thresholds of both inputs and outputs from the CRG20. The logic thresholds are shown below. For inputs to the CRG20, the threshold is 0.6*5.0 or 3V. Therefore a 3.3V system shouldn’t need any level shifting if the Logic High can be guaranteed to be above 3V. Logic Low will be correctly detected. For outputs from the CRG20, the levels will have to be reduced unless the 3.3V system has “5V Tolerant” inputs. A resistor is normally all that is required to achieve this, the value of which depends on the input resistance of the 3.3V system.

      What is the Moisture Sensitivity Level (MSL) for CRG20?

      We are often asked about MSL in relation to CRG20.  MSL specifications are usually quoted for plastic-encapsulated components.  This is because they absorb moisture which causes problems when they are subjected to soldering.  In contrast, our CRG20 gyro is a ceramic, hermetically sealed package.  An MSL specification is not normally quoted for such a package as it is not relevant - it does not absorb moisture.

      The specification gives the temperature limits for storage and provided that this is adhered to here are no particular risks associated with the long term storage of CRG20.  From the perspective of solderability, it is important to store the CRG20 in an environment that is dry, and low in sulphur, chlorine and hydrocarbons.  It is accepted practice within the industry to achieve this by vacuum packing the parts in an ESD safe moisture barrier bag.

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