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Mansa Musa was the ruler of the Mali Empire in West Africa. Details recorded here should be sourced; unknown information is left blank.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
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The Arm Advanced Microcontroller Bus Architecture (AMBA) is an open-standard, on-chip interconnect specification for the connection and management of functional blocks in system-on-a-chip (SoC) designs. It facilitates development of multi-processor designs with large numbers of controllers and components with a bus architecture. Since its inception, the scope of AMBA has, despite its name, gone far beyond microcontroller devices. Today, AMBA is widely used on a range of ASIC and SoC parts including processors used in modern portable mobile devices like smartphones. AMBA is a registered trademark of Arm Ltd.[1]
AMBA was introduced by Arm in 1996. The first AMBA buses were the Advanced System Bus (ASB) and the Advanced Peripheral Bus (APB). In its second version, AMBA 2 in 1999, Arm added AMBA High-performance Bus (AHB) that is a single clock-edge protocol. In 2003, Arm introduced the third generation, AMBA 3, including Advanced eXtensible Interface (AXI) to reach even higher performance interconnect and the Advanced Trace Bus (ATB) as part of the CoreSight on-chip debug and trace solution. In 2010 the AMBA 4 specifications were introduced starting with AMBA 4 AXI4, then in 2011[2] extending system-wide coherency with AMBA 4 AXI Coherency Extensions (ACE). In 2013[3] the AMBA 5 Coherent Hub Interface (CHI) specification was introduced, with a re-designed high-speed transport layer and features designed to reduce congestion. These protocols are today the de facto standard for embedded processor bus architectures because they are well documented and can be used without royalties.
An important aspect of an SoC is not only which components or blocks it houses, but also how they interconnect. AMBA is a solution for the blocks to interface with each other.
The objective of the AMBA specification is to:
The AMBA specification defines an on-chip communications standard for designing high-performance embedded microcontrollers. It is supported by Arm Limited with wide cross-industry participation.
The AMBA 5 specification defines the following buses/interfaces:
The AMBA 4 specification defines following buses/interfaces:
AMBA 3 specification defines four buses/interfaces:
AMBA 2 specification defines three buses/interfaces:
AMBA specification (First version) defines two buses/interfaces:
The timing aspects and the voltage levels on the bus are not dictated by the specifications.
ACE, defined as part of the AMBA 4 specification, extends AXI with additional signalling introducing system wide coherency.[4] This system coherency allows multiple processors to share memory and enables technology like Arm's big.LITTLE processing. The ACE-Lite protocol enables one-way coherency, also known as I/O coherency; for example, a network interface that can read from the caches of a fully coherent ACE processor.
AXI, the third generation of AMBA interface defined in the AMBA 3 specification, is targeted at high performance, high clock frequency system designs and includes features that make it suitable for high speed sub-micrometer interconnect:
AHB is a bus protocol introduced in Advanced Microcontroller Bus Architecture version 2 published by Arm Ltd company.
In addition to previous release, it has the following features:
A simple transaction on the AHB consists of an address phase and a subsequent data phase (without wait states: only two bus-cycles). Access to the target device is controlled through a MUX (non-tristate), thereby admitting bus-access to one bus-master at a time.
AHB-Lite is a subset of AHB formally defined in the AMBA 3 standard. This subset simplifies the design for a bus with a single master.
APB is designed for low bandwidth control accesses, for example register interfaces on system peripherals. This bus has an address and data phase similar to AHB, but a much reduced, low complexity signal list (for example no bursts). Furthermore, it is an interface designed for a low frequency system with a low bit width (32 bits).
A family of synthesizable intellectual property (IP) cores AMBA Products is licensable from Arm Limited that implement a digital bus in an SoC for the efficient moving and storing of data using the AMBA protocol specifications. The AMBA family includes AMBA Network Interconnect (CoreLink NIC-400), Cache Coherent Interconnect (CoreLink CCI-500), SDRAM memory controllers (CoreLink DMC-400), DMA controllers (CoreLink DMA-230, DMA-330), level 2 cache controllers (L2C-310), etc.
A number of manufacturers utilize AMBA buses for non-ARM designs. As an example Infineon uses an AMBA bus for the ADM5120 SoC based on the MIPS architecture.
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Interfaces are listed by their speed in the (roughly) ascending order, so the interface at the end of each section should be the fastest.  Category | |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The Arm Advanced Microcontroller Bus Architecture (AMBA) is an open-standard, on-chip interconnect specification for the connection and management of functional blocks in system-on-a-chip (SoC) designs. It facilitates development of multi-processor designs with large numbers of controllers and components with a bus architecture. Since its inception, the scope of AMBA has, despite its name, gone far beyond microcontroller devices. Today, AMBA is widely used on a range of ASIC and SoC parts including processors used in modern portable mobile devices like smartphones. AMBA is a registered trademark of Arm Ltd. AMBA was introduced by Arm in 1996. The first AMBA buses were the Advanced System Bus (ASB) and the Advanced Peripheral Bus (APB). In its second version, AMBA 2 in 1999, Arm added AMBA High-performance Bus (AHB) that is a single clock-edge protocol. In 2003, Arm introduced the third generation, AMBA 3, including Advanced eXtensible Interface (AXI) to reach even higher performance interconnect and the Advanced Trace Bus (ATB) as part of the CoreSight on-chip debug and trace solution. In 2010 the AMBA 4 specifications were introduced starting with AMBA 4 AXI4, then in 2011 extending system-wide coherency with AMBA 4 AXI Coherency Extensions (ACE). In 2013 the AMBA 5 Coherent Hub Interface (CHI) specification was introduced, with a re-designed high-speed transport layer and features designed to reduce congestion. These protocols are today the de facto standard for embedded processor bus architectures because they are well documented and can be used without royalties.
The Advanced eXtensible Interface (AXI) is an on-chip communication bus protocol and is part of the Advanced Microcontroller Bus Architecture specification (AMBA). AXI is royalty-free and its specification is freely available from ARM. AMBA AXI specifies many optional signals, which can be included depending on the specific requirements of the design, making AXI a versatile bus for numerous applications. While the communication over an AXI bus is between a single initiator and a single target, the specification includes detailed descriptions and signals to include N:M interconnects, able to extend the bus to topologies with multiple initiators and targets. AXI3 was introduced in 2003 with the AMBA3 specification. In 2010, a new revision of AMBA, AMBA4, defined the AXI4, AXI4-Lite and AXI4-Stream protocols. AMBA AXI4, AXI4-Lite and AXI4-Stream have been adopted by Xilinx and many of its partners as a main communication bus in their products. AMBA5 with AXI5 was released in 2022, adding atomicity, data protection, and cache operations. A new ACE (AXI Coherency Extension) is specified.
AXI or variation, may refer to: Automated X-ray inspection Advanced eXtensible Interface of ARM for Advanced Microcontroller Bus Architecture (AMBA) AXI car, a right-hand-drive version of the DMC DeLorean Aeron International Airlines (ICAO airline code: AXI), see List of airline codes (A) Axitinib (PDB code AXI) AxiCorp GmbH, a German pharmaceutical company, subsidiary of Biocon S55 Axi Expressway, see List of provincial expressways of China Axi (Chinese: 阿希村), Qaka, Xinjiang, China; a village Axi Township (Chinese: 阿西乡), Zoigê County, Ngawa, Sichuan, China; see List of township-level divisions of Sichuan Axi language, a Loloish language spoken by the Yi people Axi Stachowitsch (1918–2013), Austrian-Russian academic Robert Axi, 15th century Member of Parliament in England "axi-", a term pertaining to axis; see List of Greek and Latin roots in English/A–G
A microcontroller (MC, uC, or μC) or microcontroller unit (MCU) is a small computer on a single integrated circuit. A microcontroller contains one or more processor cores along with memory and programmable input/output peripherals. Program memory in the form of NOR flash, OTP ROM, or ferroelectric RAM is also often included on the chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general-purpose applications consisting of various discrete chips. In modern terminology, a microcontroller is similar to, but less sophisticated than, a system on a chip (SoC). A SoC may include a microcontroller as one of its components but usually integrates it with advanced peripherals like a graphics processing unit (GPU), a Wi-Fi module, or one or more coprocessors. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys, and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make digital control of more devices and processes practical. Mixed-signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems. In the context of the Internet of things, microcontrollers are an economical and popular means of data collection, sensing and actuating the physical world as edge devices. Some microcontrollers may use four-bit words and operate at frequencies as low as 4 kHz for low power consumption (single-digit milliwatts or microwatts). They generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (with the CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor (DSP), with higher clock speeds and power consumption.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →The Greenwood District.