A20

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A20
Allwinner_A20.jpg
Manufacturer Allwinner
CPU Dual-Core ARM Cortex-A7
Memory LPDDR3/DDR3/LPDDR2
GPU Mali400 MP2
Connectivity
Video HDMI 1.4, CVBS, YPbPr, VGA, CPU/RGB/LVDS LCD
Audio I2S, PCM, AC97
Storage MMC, NAND
USB OTG, 2x Host
Release Date December 2012
Website Product Page

Allwinner A20 (sun7i) SoC features a Dual-Core Cortex-A7 ARM CPU, and a Mali400 MP2 GPU from ARM.

Allwinner A20 is a low-end (budget) version of the A31. It shares its Cortex-A7 ARM CPU architecture, but at the same time it is also pin-to-pin compatible with A10.

A20 is fully supported by the community from linux-sunxi 3.4 kernel and later.

Contents

Overview

A20 CPU consists of dual ARM Cortex-A7 cores, and integrates the Mali400 MP2 GPU. Together with CedarX multimedia processing unit that is capable of up to 2160p (3840x1080@30fps 4k resolution or 1080p 3D decoding) video decoding, with integrated HDMI 1.4 output support, and H.264 HP (High Profile) in 1080p at 30fps video encoding.

Main components of the A20

  • CPU: Dual-Core ARM Cortex-A7 1GHz Processor which have both VFP4 and NEON SIMD co-processors that share 32 floating point double-precision registers together[1]:
    • FPU: standard ARM VFPv4-D32 FPU Floating Point Unit
    • SIMD: NEON (ARM's extended general-purpose SIMD vector processing extension engine)
  • GPU: Mali400 MP2
  • VPU: CedarX (Video Processor Unit for audio and video hardware decoding or encoding)
  • HDMI-transmitter: HDMI CEC (Consumer Electronics Control)

Cortex-A7

Cortex-A7 is 100% ISA compatible with the Cortex-A15, this includes the new virtualization instructions, integer divide support and 40-bit memory addressing. Any code running on an A15 can run on a Cortex A7, just slower. This is a very important feature as it enables SoC vendors to build chips with both Cortex A7 and Cortex A15 cores, switching between them depending on workload requirements. ARM calls this a big.LITTLE configuration.[2][3][4]

Virtualization

Cortex A7 and A15 includes hardware virtualization support.

On the kvm branch of kernel.org, there is description of Cortex-A15 Virtualization extensions VGIC registers :

After the ARM Cortex-A7 documentation:

  • GIC memory MAP on Cortex-A7[5]:
0x4000-0x4FFF      Virtual interface control, common base address
0x5000-0x5FFF   Virtual interface control, processor-specific base address
0x6000-0x7FFF   Virtual CPU interface
  • Virtual Maintenance Interrupt (PPI6)[6]
  • 2 virtual interrupt signals, nVIRQ and nVFIQ[7]
  • With MMU-400, Intermediate Physical Address (IPA) ca be used by guest OS[8]

A20 SoC Features

A20 SoC on a Cubieboard2
  • CPU
    • ARM Cortex-A7 Dual-Core (revision r0p4)
    • 256KiB L2-Cache (shared between two cores)
    • 32KiB (Instruction) / 32KiB (Data) L1-Cache per core
    • SIMD NEON, VFP4
    • Virtualization
    • Large Physical Address Extensions (LPAE) 1TB
  • GPU
    • ARM Mali400 MP2
    • Featuring 1 vertex shader (GP) and 2 fragment shaders (PP).
    • Complies with OpenGL ES 2.0
  • Memory
    • LPDDR2/DDR3/DDR3L controller
    • NAND Flash controller and 64-bit ECC
  • Video
    • HD H.264 2160P video decoding
    • Full HD video decoding
    • BD Directory, BD ISO and BD m2ts video decoding
    • H.264 High Profile 1080P@30fps encoding
    • 3840×1080@30fps 3D decoding
    • Complies with RTSP, HTTP,HLS,RTMP,MMS streaming media protocol
  • Display
    • Support multi-channel HD display
    • Integrated HDMI 1.4
    • CPU/RGB/LVDS LCD interface 1920×1080 resolution
    • CVBS/YPbPr/VGA support
    • Integrated TV decoder
  • Camera
    • Integrated parallel 8-bit I/F YUV sensor
    • Integrated 24-bit parallel YUV 444 I/F
    • 5M/8M CMOS sensor support
    • Dual-sensor support
  • Audio
    • Integrated HI-FI 100dB Audio Codec
    • Dual MIC noise cancellation

Documentation

Latest documentation is available on AllWinners documentation repository on Github

Software

Original SDKs

We have made some SDKs available on our server:

GPL Violations

The publically available SDKs contain kernel and u-boot trees which include and depend on several binaries. Allwinner is violating the GPL quite directly here.

A20_SDK_20130319 SDK

kernel

u-boot

Devices

See also

References

  1. Cortex-A7 MPCore Technical Reference Manual — 1.3. Features
  2. http://www.anandtech.com/show/4991/arms-cortex-a7-bringing-cheaper-dualcore-more-power-efficient-highend-devices
  3. http://en.wikipedia.org/wiki/ARM_Cortex-A7_MPCore
  4. http://www.arm.com/products/processors/cortex-a/cortex-a7.php
  5. Cortex-A7 MPCore Technical Reference Manual - 8.2.1. GIC memory-map
  6. Cortex-A7 MPCore Technical Reference Manual - 8.2.2. Interrupt sources
  7. Cortex-A7 MPCore Technical Reference Manual - 8.2.4. GIC configuration
  8. CoreLink MMU-400 System Memory Management Unit Technical Reference Manual - 1.1. About the MMU-400

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