EFM32WG Datasheet, PDF (21/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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5.2.3.1 Arbitration
The Bus Matrix uses a round-robin arbitration algorithm which enables high throughput and low latency
while starvation of simultaneous accesses to the same bus slave are eliminated. Round-robin does not
assign a fixed priority to each bus master. The arbiter does not insert any bus wait-states.
5.2.3.2 Access Performance
The Bus Matrix is a multi-layer energy optimized AMBA AHB compliant bus with an internal bandwidth
equal to 4 times a single AHB-bus.
The Bus Matrix accepts new transfers initiated by each master in every clock cycle without inserting
any wait-states. The slaves, however, may insert wait-states depending on their internal throughput and
the clock frequency.
The Cortex-M4, the DMA Controller, and the peripherals run on clocks that can be prescaled separately.
When accessing a peripheral which runs on a frequency equal to or faster than the HFCORECLK, the
number of wait cycles per access, in addition to master arbitration, is given by:
Memory Wait Cycles with Clock Equal or Faster than HFCORECLK
N_cycles = 2 + N_{slave cycles},
(5.3)
where N_{slave cycles} is the wait cycles introduced by the slave.
When accessing a peripheral running on a clock slower than the HFCORECLK, wait-cycles are
introduced to allow the transfer to complete on the peripheral clock. The number of wait cycles per
access, in addition to master arbitration, is given by:
Memory Wait Cycles with Clock Slower than CPU
N_cycles = (2 + N_{slave cycles}) x f_HFCORECLK/f_HFPERCLK,
where N_{slave cycles} is the number of wait cycles introduced by the slave.
More details on clocks and prescaling can be found in Chapter 11 (p. 124) .
(5.4)
5.3 Access to Low Energy Peripherals (Asynchronous Registers)
5.3.1 Introduction
The Low Energy Peripherals are capable of running when the high frequency oscillator and core system
is powered off, i.e. in energy mode EM2 and in some cases also EM3. This enables the peripherals to
perform tasks while the system energy consumption is minimal.
The Low Energy Peripherals are:
• Liquid Crystal Display driver - LCD
• Low Energy Timer - LETIMER
• Low Energy UART - LEUART
• Pulse Counter - PCNT
• Real Time Counter - RTC
• Watchdog - WDOG
• Low Energy Sensor Interface - LESENSE
• Backup RTC - BURTC
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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