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resources:eval:user-guides:pioneer1-wiredcbm [04 Jul 2019 10:23]
Richard Anslow
resources:eval:user-guides:pioneer1-wiredcbm [16 Feb 2021 10:34] (current)
Richard Anslow
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 The following guidelines apply for the direct SPI to RS-485 link designs (DEMO-CbM-Slave2-Z and DEMO-CbM-Slave3-Z). The following guidelines apply for the direct SPI to RS-485 link designs (DEMO-CbM-Slave2-Z and DEMO-CbM-Slave3-Z).
-The SPI to RS-485 link design includes ​a SPI clock transfer over RS-485 (SCLK) and a power over data lines implementation (phantom power), where data and power share the same twisted pair (SPI MISO).+The SPI to RS-485/​RS-422 ​link designs include ​a SPI clock transfer over RS-422 (SCLK) and a power over data lines implementation (phantom power), where data and power share the same twisted pair (SPI MISO).
  
 **Cable Effects** **Cable Effects**
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 ** Typical Performance** ** Typical Performance**
-  * Typical SPI SCLK rate vs. cable length performance in a Phantom Power network is characterized in Figure 2. This shows  DEMO-CbM-Slave3-Z (non-isolated slave) error free performance when  porting the ADcmXL3021 SPI output over cabling. ​+  * Typical SPI SCLK rate vs. cable length performance in a Phantom Power network is characterized in Figure 2. This shows  DEMO-CbM-Slave3-Z (non-isolated slave) and DEMO-CbM-Slave2-Z (isolated slave)error free performance when  porting the ADcmXL3021 SPI output over cabling. ​
  
-{{:​resources:​eval:​user-guides:​pioneer_1_kit_sclk_vs_dr_wiki1.png|}}+{{ :​resources:​eval:​user-guides:​pioneer_1_kit_sclk_vs_dr_wiki_rev1.png?600 |}}
  
 **Figure 2. SPI SCLK vs. Cable Length Typical Performance** **Figure 2. SPI SCLK vs. Cable Length Typical Performance**
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   * Low complexity isolated Slave Sensor interface board DEMO-CbM-Slave2-Z.   * Low complexity isolated Slave Sensor interface board DEMO-CbM-Slave2-Z.
   * 2m RJ50 cable (194612-02) and 10m RJ50 cable (194612-10)   * 2m RJ50 cable (194612-02) and 10m RJ50 cable (194612-10)
-  * AC/DC Power Supply - EU/​UK/​US/​AU ​+  * AC/DC Power Supply - EU/UK/US/AU
  
 The following is supplied as part of the **EV-CbM-Pioneer1-2Z** demo kit: The following is supplied as part of the **EV-CbM-Pioneer1-2Z** demo kit:
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 The following steps describe a typical setup, as shown in Figure 3, to communicate over a SPI to RS-485 link using either DEMO-CbM-Slave2-Z or DEMO-CbM-Slave3-Z:​ The following steps describe a typical setup, as shown in Figure 3, to communicate over a SPI to RS-485 link using either DEMO-CbM-Slave2-Z or DEMO-CbM-Slave3-Z:​
-  - Ensure that the following jumper selections are made for the DEMO-CbM-Master-Z:​ LK8: position B, and LK5 and LK6: Position A.+  - Ensure that the following jumper selections are made for the DEMO-CbM-Master-Z:​ LK8: position A or position B, and LK5 and LK6: Position A. The LK8 jumper needs to be set, but the position is at the user's discretion.
   - Connect the supplied 2-meter RJ50 cable to the J10 RJ50 connector on the DEMO-CbM-Master-Z as indicated in Figure 4. Do not confuse this with the RJ45 connector (J1). Inserting RJ50 cable plugs into RJ45 connectors will damage the plug/​connector contacts.   - Connect the supplied 2-meter RJ50 cable to the J10 RJ50 connector on the DEMO-CbM-Master-Z as indicated in Figure 4. Do not confuse this with the RJ45 connector (J1). Inserting RJ50 cable plugs into RJ45 connectors will damage the plug/​connector contacts.
   - Connect the Cypress Evaluation Board CYUSB3KIT-003 as shown in Figure 4 below. J6 and J7 on the DEMO-CbM-Master-Z align with the like-named J6 and J7 on the CYUSB3KIT-003.   - Connect the Cypress Evaluation Board CYUSB3KIT-003 as shown in Figure 4 below. J6 and J7 on the DEMO-CbM-Master-Z align with the like-named J6 and J7 on the CYUSB3KIT-003.
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   - Connect the ADcmXL3021 XL module hi-rose connector (male) to the hi-rose connector (female) on the DEMO-CbM-Slave3-Z. Refer to Figure 5 for connector orientation. Ensure that Pin1 on both connectors is aligned as shown.   - Connect the ADcmXL3021 XL module hi-rose connector (male) to the hi-rose connector (female) on the DEMO-CbM-Slave3-Z. Refer to Figure 5 for connector orientation. Ensure that Pin1 on both connectors is aligned as shown.
   - Connect the Power Supply to the barrel connector on the DEMO-CbM-Master-Z. The power supply should be set to a minimum of +6 V and a maximum of +12 V. This provides power to both master and slave boards.   - Connect the Power Supply to the barrel connector on the DEMO-CbM-Master-Z. The power supply should be set to a minimum of +6 V and a maximum of +12 V. This provides power to both master and slave boards.
 +  - **Note: the Master board barrel connector is configured for a positive centre tip power supply. For the demo kit power supply –-> connect the positive centre (+) to the positive centre (+) on the small tip adaptors.**
   - Connect the USB 3.0 cable supplied with the CYUSB3KIT-003 to a USB 3.0 port on your computer.   - Connect the USB 3.0 cable supplied with the CYUSB3KIT-003 to a USB 3.0 port on your computer.
  
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   - Open the Vibration Evaluation software version 2.1.8 on your computer.   - Open the Vibration Evaluation software version 2.1.8 on your computer.
-  - Open the ‘Comm’ menu and select ‘SPI’. Set the SPI SCLK to 2.MHz and hit ‘update’.+  - Open the ‘Comm’ menu and select ‘SPI’. Set the SPI SCLK to 2.MHz and hit ‘update’.
   - Select Manual Time Capture (MTC) from the Mode Selection drop down menu, and hit the start button.   - Select Manual Time Capture (MTC) from the Mode Selection drop down menu, and hit the start button.
-  - For the setup described in Figure 3 – the X, Y, and Z axis MTC measurements are shown in Figure 6.+  - For the Typical ​setup described in Figure 3 – the X, Y, and Z axis MTC measurements are shown in Figure 6.
   - The corresponding Manual Fast Fourier Transform (MFFT) measurements are shown in Figure 7.   - The corresponding Manual Fast Fourier Transform (MFFT) measurements are shown in Figure 7.
  
-<note tip>Tip: If the system is unresponsive,​ or data plots are erroneous, then press the S2 pushbutton switch on the DEMO-CbM-Slave3-Z to reset the ADcmXL3021.</​note>​+<note tip>Tip: If the system is unresponsive,​ or data plots are erroneous, then press the S2 pushbutton switch on the DEMO-CbM-Slave2-Z / DEMO-CbM-Slave3-Z to reset the ADcmXL3021.</​note>​
  
 {{ :​resources:​eval:​user-guides:​mtc.png |}} {{ :​resources:​eval:​user-guides:​mtc.png |}}
-**Figure 6. Typical Manual Time Capture Plot - corresponding to Figure ​Typical Setup**+**Figure 6. Typical Manual Time Capture Plot - corresponding to Figure ​Typical Setup**
  
 {{ :​resources:​eval:​user-guides:​mfft.png |}} {{ :​resources:​eval:​user-guides:​mfft.png |}}
-**Figure 7. Typical Manual FFT Plot - corresponding to Figure ​Typical Setup**+**Figure 7. Typical Manual FFT Plot - corresponding to Figure ​Typical Setup**
  
 ==== GUI measurements for a non-Repetitive Vibration Source ==== ==== GUI measurements for a non-Repetitive Vibration Source ====
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 Schematics, layout, BOM, and Gerber file for the DEMO-CbM-Expandr-Z:​ Schematics, layout, BOM, and Gerber file for the DEMO-CbM-Expandr-Z:​
 {{ :​resources:​eval:​user-guides:​demo-cbm-expandr-z_zip.zip |click here to download}} {{ :​resources:​eval:​user-guides:​demo-cbm-expandr-z_zip.zip |click here to download}}
 +
 +===== LTspice Simulation =====
 +A simplified power over data wires simulation circuit is provided in Figure 10. This circuit uses LTC2862 RS-485 transceiver LTspice macromodels and 1 mH inductors (Wurth 74477830). LTspice includes real inductor models, which include device parasitics, enabling closer correlation between simulation and real design performance. The DC blocking capacitor values are 10 µF. In general, using larger inductor and capacitor values enable a lower data rate performance on the communication network. The simulated test case is a 250 kHz data rate, which roughly corresponds to 100 meters of cabled communication when porting clock synchronised SPI over an RS-485 interface. The input voltage waveform used in the simulation corresponds to a worst-case dc content, with a 16-bit word and all logic high bits. Simulation results are presented in Figures 11 and 12. The input voltage waveform (VIN) matches the output at the remote powered device (no communication errors). Figure 12 presents a zoomed-in view of the bus voltage differential waveform (voltage A – voltage B) for droop analysis. The voltage at the remote sensor node, extracted from the L2 inductor (V(pout)) provides a power supply rail of 5V±1mV.
 +
 +{{ :​resources:​eval:​user-guides:​new.png |}}
 +**Figure 10. Engineered Power LTspice simulation circuit using LTC2862 (RS-485) and 1mH Wurth Inductor 74477830**
 +
 +{{ :​resources:​eval:​user-guides:​11.png |}}
 +**Figure 11. Simulation Result with RS-485 bus differential voltage V(A,B) , and droop points X and Y**
 +
 +{{ :​resources:​eval:​user-guides:​12.png |}}
 +**Figure 12. Droop analysis for point X and Y**
 +
 +{{ :​resources:​eval:​user-guides:​13.png |}}
 +
 +The VDROOP, VPEAK, and TDROOP are measured using the Figure 11 and 12 LTspice waveform. The L and C values are then calculated using equations 2 and 4. It depends where you measure on the waveform, however, the calculated L value is 1 to 3mH as shown in Table 1. Measuring at point X (Figure 12) is most accurate and yields the correct inductance value of approximately 1 mH. The high pass filter frequency (equation 6) is simply a function of the droop time and voltage, and for point X is approximately equates to 250 kHz/32 for 1 bit (half clock cycle), which matches the input waveform (V3) shown in the Figure 10 schematic.
 +
 +**Table 1**
 +{{ :​resources:​eval:​user-guides:​table.png |}}
 +
 +When simulating Figure 10 it is also worth noting that the C8 capacitor is recommended to reduce voltage overshoot at the sensor (Vpout at power extraction node). With C8 added the overshoot is maximum 47mV and settles to within 1mV of the desired 5VDC within 1.6ms. Simulating without a C8 capacitor results in an underdamped system, with 600mV overshoot, and a permanent 100mV of voltage oscillation from the 5V dc target.
 +
 +LTSpice models are available here:
 +{{ :​resources:​eval:​user-guides:​podl_article.zip |click here to download}}
  
 ===== Change Log ===== ===== Change Log =====
  
-June 2019. Initial Release+*July 2019. Initial Release
 + 
 +*August 2019. Added additional information on demo power supply configuration.
  
 +*February 2021. Added LTspice models for engineered power.
  
  
resources/eval/user-guides/pioneer1-wiredcbm.1562228587.txt.gz · Last modified: 04 Jul 2019 10:23 by Richard Anslow