# Cypress Developer CommunityTM

## CX3 – Frequently asked questions - Hardware

Summary: 1 Reply, Latest post by RSKV on 29 Apr 2014 01:15 PM PDT
Cypress Employee
1134 posts

Hardware

1.      - Is it possible to use a single clock source for the CX3?

Yes. It is possible to use a single clock source of 19.2MHz. This clock input should be connected to the “REFCLK” and “CLKIN”. But a clock buffer should be used to isolate these two clock signals.

The “CLKIN32” is an optional signal. This needs to be supplied with 32 KHz clock input if you want to use the “watchdog” feature.

2.      - Can CX3 provide a “Clock out” which can be used as a “Clock input” for Image sensor or Image Signal processor?

Yes. CX3 provides a clock output signal “MCLK”. The output frequency of this signal is programmable. The value of the clock output can be selected between 16KHz to 125 MHz. This signal belongs to “VDDIO1” voltage domain.

3.      - How much current does CX3 draw from the USB VBUS supply?

The total current CX3 consumes from the 5V source in normal mode will be around 112.6mA. This is worst case (1080p30fps, 24bit data bus, 6V at VBUS, 3.6V for IO supply, 1.25 for Core/U3).

Note: We considered 5V to 1.2V/1.8V/3.3V Switching regulators with ~85% efficiency for this calculation. Find below the table showing the calculation.

If we use only USB2.0 port of CX3 then the current consumption will be around 98.6mA.

When the device is standby mode it will consume around 68 uA and in suspend mode it will consume 3.2mA.

Find below the calculation for the power consumption

 Parameter Voltage V Current in mA Power in Watts External Power converter efficiency Input power in Watts Core 1.25 159.2 0.199 Vbus 6 22.6 0.136 U3Tx 1.25 17.1 0.021 U3Rx 1.25 30.2 0.038 IO supply 3.6 23.5 0.085 Total power 0.478 0.85 0.563 Current from VBUS 5 112.6

4.      - Does OmniVision Image sensors like OV5640, OV10822 with SCCB port work with CX3?

As far as SCCB vs I2C, the OmniVision defined SCCB, is supposed to treat the “Ack” bit as a don’t care (and therefore have the transaction continue without checking for errors), but in practice we have seen that OV sensors do set the “Ack” bit after each transaction and works fine with CX3’s I2C master.

5.      - Does CX3 support Image Sensors with serial LVDS, SubLVDS or HiSPi interface?

No. CX3 supports only the MIPI CSI-2 image sensors. Image sensors with serial LVDS, Sub LVDS, HiSPi interface can be interfaced to FX3 using external serial LVDS to Parallel converters.

6.      - Is it possible to connect two MIPI CSI-2 image sensors with 1 or 2 Lanes with one CX3?

No. It is not possible to connect two image sensors to one CX3. You need an external ISP with two image sensor input channels and one MIPI CSI-2 output interface to connect two sensors to one CX3.

7.      - Does CX3 have some method to control LED using PWM? Will it need additional microcontroller for this?

CX3 has GPIOs that can provide PWM output. CX3’s built-in microcontroller can be used to control the LED.

8.     -  What are the routing guidelines to be followed while routing the MIPI CSI-2 lines?

The “AN70707 - FX3/FX3S Hardware Design Guidelines” application note discusses recommended practices for FX3/FX3 hardware design which are also applicable to CX3.

For MIPI CSI-2 signals, additional routing guidelines should be followed which are provided below.

a.      The inter lane (between two MIPI CSI lane signal pairs) length mismatch should be < 1.5 mm

b.      The space between the P and N signal tracks should be twice the width of the tracks

c.      The length of the traces on the board should not exceed 100 mm.

d.      Transmission line impedance (Z0) for the tracks of differential pair should be 100 Ω +/- 10%.

e.      The intra lane (between P and N lines of a pair) length mismatch should be < 0.5 mm

Thanks,

Sai Krishna.

Cypress Employee
1134 posts

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MicrosoftInternetExplorer4

Question: Is "Cypress EZ-USB® CX3 - Programmable MIPI-USB 3.0 camera controller" USB certified?

Answer: Yes. Cypress CX3 is certified by USB-IF in Category "Development > Peripheral Silicon > SuperSpeed > Other". The TID # 340880047

Find below the link for Cypress CX3 in the USB-IF website.

http://www.usb.org/kcompliance/view/view_item?item_key=8b303d9f7b3c0df642d7dce43af47d6ffc7235b4&referring_url=/kcompliance

Thanks,
Sai Krishna

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