AHB multilayer

The CPU and all of the EasyDMAs are AHB bus masters on the AHB multilayer, while the RAM and various other modules are AHB slaves.

See Block diagram for an overview of which peripherals implement EasyDMA.

The CPU has exclusive access to all AHB slaves except for the RAM that can also be accessed by the EasyDMA.

Access rights to each of the RAM AHB slaves are resolved using the priority of the different bus masters in the system

See AHB multilayer priorities for information about the priority of the different AHB bus masters in the system. It is possible for two or more bus masters to have the same priority in cases where it is guaranteed by design that the related masters will never be able to access the same slave at the same time.

AHB multilayer priorities

Each master connected to the AHB multilayer is assigned a priority.

Table 1. AHB bus masters
Bus master name Priority Description
CPU Highest priority  
SPIS1   Applies to SPIM1, SPIS1, TWIM1, TWIS1
RADIO    
CCM/ECB/AAR    
SAADC    
UARTE    
SERIAL0   Applies to SPIM0, SPIS0, TWIM0, TWIS0
SERIAL2   Applies to SPIM2, SPIS2
NFCT    
I2S   I2S
PDM   PDM
PWM Lowest priority Applies to PWM0, PWM1, PWM2

Documentation feedback | Developer Zone | Updated 2017-02-09