Method and apparatus for providing input to a camera serial interface transmitter

• US 9,491,495 B2
• Filed: 01/16/2015
• Issued: 11/08/2016
• Est. Priority Date: 01/16/2015
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Analog Devices Global Unlimited Company (Analog Devices, Inc.)
• Inventors: Bohm, Chris W., Kamath, Narsimh Dilip
• Primary Examiner(s): JAIN, RAJ K
• Application Number:
  US14/598,299
• Publication Number:
  US 20160212456A1
• Time in Patent Office: 662 Days
• US Class Current: 1/1
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: G06F 13/38 Information transfer, e.g. on bus G06F13/14 takes precedence
• CPC Class Codes: G06F 13/4291 using a clocked protocol
• CPC Class Codes: H04H 20/62 for transportation systems, e.g. in vehicles
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 25/4904 using self-synchronising codes, e.g. split-phase codes
• CPC Class Codes: H04L 25/493 by transition coding, i.e. the time-position or direction of a transition being encoded before transmission
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/23602 Multiplexing isochronously with the video sync, e.g. according to bit-parallel or bit-serial interface formats, as SDI
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/41422 located in transportation means, e.g. personal vehicle arrangements specially adapted for transportation systems in broadcast systems H04H20/62
• CPC Class Codes: H04N 21/4223 Cameras H04N23/00 takes precedence
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A system for receiving at least two data streams and providing a single input data stream to a MIPI'"'"'s CSI Tx is disclosed. The two received data streams are written into respective data buffers. The system includes a control logic configured to control reading of data stored in the buffers to a multiplexer, the read-side clock being a multiple of a frequency of a fixed frequency clock. The control logic is further configured to control the multiplexer to combine data read from each buffer that corresponds to a complete unit of data into a separate portion and multiplex the separate portions into the input data stream. In this manner, two data streams may be transmitted using a single CSI Tx. When the two data streams are received by the system from an APIX interface, the system provides a bridge between the APIX interface and MIPI'"'"'s CSI Tx.

Claims

1. A system for providing an input data stream to a transmitter of a Camera Serial Interface (CSI Tx), wherein:

the input data stream comprises data of at least a first data stream and a second data stream,

the first data stream comprises data organized in first units of data,

the second data stream comprises data organized in second units of data,

the data of the first data stream is to be written into a first buffer, and

the data of the second data stream is to be written into a second data buffer,

the system comprising;

a multiplexer; and

a control logic configured to;

issue a first read-enable signal to transfer at least a part of the data stored in the first buffer to the multiplexer at a predefined multiple of a frequency of a fixed frequency clock,

issue a second read-enable signal to transfer at least a part of the data stored in the second buffer to the multiplexer at the predefined multiple of the frequency of the fixed frequency clock,

control the multiplexer to combine all data transferred from the first buffer and corresponding to a complete unit of the first units of data into a first portion,

control the multiplexer to combine all data transferred from the second buffer and corresponding to a complete unit of the second units of data into a second portion,

control the multiplexer to multiplex the first portion and the second portion into the input data stream,

provide the input data stream to the CSI Tx.

2. The system according to claim 1, wherein:

each of the first and second data streams is received by the system as an output of an Automotive Pixel Link (APIX) interface,

the first data stream comprises a first video stream and the second data stream comprises a second video stream,

each unit of the first units of data comprises a complete line comprising a first number of pixels and each unit of the second units of data comprises a complete line comprising a second number of pixels,

the control logic is further configured to receive indications from the APIX interface when each complete line of each of the first and second video streams begins and ends, and

the control logic is further configured to control the CSI Tx to enter a high-speed (HS) mode to transmit each complete line of each of the first and second video streams in a separate packet.

3. The system according to claim 2, wherein the indications received from the APIX interface comprise horizontal sync signals.

4. The system according to claim 1, wherein the control logic is further configured to:

provide to the CSI Tx an identification of the complete unit of the first units of data included in the first portion and an indication that the first portion contains data of the first data stream, and

provide to the CSI Tx an identification of the complete unit of the second units of data included in the second portion and an indication that the second portion contains data of the second data stream.

5. The system according to claim 1, wherein:

the first data stream comprises a first video stream and the second data stream comprises a second video stream,

each unit of the first units of data comprises a complete line comprising a first number of pixels and each unit of the second units of data comprises a complete line comprising a second number of pixels,

the system further comprises the first buffer and the second buffer,

the first buffer comprises a line buffer for storing at least a portion of the complete line comprising the first number of pixels and the second buffer comprises a line buffer for storing at least a portion of the complete line comprising the second number of pixels.

6. The system according to claim 1, wherein the system further comprises the fixed frequency clock.

7. The system according to claim 6, wherein the system further comprises a phase locked loop coupled to the output of the fixed frequency clock.

8. The system according to claim 1, wherein the fixed frequency clock comprises an XTAL clock.

9. The system according to claim 1, wherein the multiple of the frequency of the fixed frequency clock is selected based on minimum frequency requirements derived from the sum of data rates of the first and second data streams.

10. The system according to claim 1, wherein the system is implemented in an application specific integrated circuit (ASIC).

11. The system according to claim 1, wherein at least a part of the system is implemented in a programmable hardware.

12. A method for providing an input data stream to a transmitter of a Camera Serial Interface (CSI Tx), wherein:

the input data stream comprises data of at least a first data stream and a second data stream,

the first data stream comprises data organized in first units of data,

the second data stream comprises data organized in second units of data,

the data of the first data stream is to be written into a first buffer, and

the data of the second data stream is to be written into a second data buffer,

the method comprising;

issuing a first read-enable signal to transfer at least a part of the data stored in the first buffer to a multiplexer at a predefined multiple of a frequency of a fixed frequency clock,

issuing a second read-enable signal to transfer at least a part of the stored in the second buffer to the multiplexer at the predefined multiple of the frequency of the fixed frequency clock,

controlling the multiplexer to combine all data transferred from the first buffer and corresponding to a complete unit of the first units of data into a first portion,

controlling the multiplexer to combine all data transferred from the second buffer and corresponding to a complete unit of the second units of data into a second portion,

controlling the multiplexer to multiplex the first portion and the second portion into the input data stream,

providing the input data stream to the CSI Tx.

13. The method according to claim 12, wherein:

each of the first and second data streams is received by the system as an output of an Automotive Pixel Link (APIX) interface,

the first data stream comprises a first video stream and the second data stream comprises a second video stream,

each unit of the first units of data comprises a complete line comprising a first number of pixels,

each unit of the second units of data comprises a complete line comprising a second number of pixels, and

the method further comprises;

receiving indications from the APIX interface when each complete line of each of the first and second video streams begins and ends, and

controlling the CSI Tx to enter a high-speed mode to transmit each complete line of each of the first and second video streams in a separate packet.

14. The method according to claim 13, wherein the indications received from the APIX interface comprise horizontal sync signals.

15. The method according to claim 12, further comprising:

providing to the CSI Tx an identification of the complete unit of the first units of data included in the first portion and an indication that the first portion contains data of the first data stream, and

providing to the CSI Tx an identification of the complete unit of the second units of data included in the second portion and an indication that the second portion contains data of the second data stream.

16. The method according to claim 12, wherein the fixed frequency clock comprises an XTAL clock.

17. The method according to claim 12, wherein the multiple of the frequency of the fixed frequency clock is selected based on minimum frequency requirements derived from the sum of data rates of the first and second data streams.

18. The method according to claim 12, further comprising:

obtaining information indicative of a data rate of the first data streams and of a data rate of the second data stream, and

selecting the multiple of the frequency of the fixed frequency clock based on minimum frequency requirements derived from a sum of the data rate of the first data stream and the data rate of the second data stream.

19. A non-transitory computer readable storage medium storing software code portions configured for, when executed on a processor, carrying out a method for providing an input data stream to a transmitter of a Camera Serial Interface (CSI Tx) wherein:

the input data stream comprises data of at least a first data stream and a second data stream,

the first data stream comprises data organized in first units of data,

the second data stream comprises data organized in second units of data,

the data of the first data stream is to be written into a first buffer, and

the data of the second data stream is to be written into a second data buffer,

the method comprising;

issuing a first read-enable signal to transfer at least a part of the data stored in the first buffer to a multiplexer at a predefined multiple of a frequency of a fixed frequency clock,

issuing a second read-enable signal to transfer at least a part of the stored in the second buffer to the multiplexer at the predefined multiple of the frequency of the fixed frequency clock,

controlling the multiplexer to combine all data transferred from the first buffer and corresponding to a complete unit of the first units of data into a first portion,

controlling the multiplexer to combine all data transferred from the second buffer and corresponding to a complete unit of the second units of data into a second portion,

controlling the multiplexer to multiplex the first portion and the second portion into the input data stream,

providing the input data stream to the CSI Tx.

20. The non-transitory computer readable storage medium according to claim 19, wherein:

each of the first and second data streams is received by the system as an output of an Automotive Pixel Link (APIX) interface,

the first data stream comprises a first video stream and the second data stream comprises a second video stream,

each unit of the first units of data comprises a complete line comprising a first number of pixels,

each unit of the second units of data comprises a complete line comprising a second number of pixels, and

the method further comprises;

receiving indications from the APIX interface when each complete line of each of the first and second video streams begins and ends, and

controlling the CSI Tx to enter a high-speed mode to transmit each complete line of each of the first and second video streams in a separate packet.