NRF9160-SICA-R7 datasheet(270/400 Pages) NORDIC

270 / 400 page

Peripherals

• Read will always return a zero value

No exceptions are thrown when a non-secure access targets a register or bitfield controlling a secure

channel. For example, if the bit i is set in the DPPI[n].PERM register (declaring the DPPI channel i as

secure), then:

• Non-secure write accesses to registers CHEN, CHENSET and CHENCLR will not be able to write to bit i of

those registers

• Non-secure write accesses to registers TASK_CHG[j].EN and TASK_CHG[j].DIS will be ignored if the

channel group j contains at least one channel defined as secure (it can be the channel i itself or any

channel declared as secured)

• Non-secure read accesses to registers CHEN, CHENSET and CHENCLR will always read zero for the bit at

position i

For the channel configuration registers (DPPIC.CHG[n]), access from non-secure code is only possible if the

included channels are all non-secure, whether the channels are enabled or not. If a DPPIC.CHG[g] register

included one or more secure channels, then the group gis considered as secure and only a secure transfer

can read or write DPPIC.CHG[g]. A non-secure write will be ignored and a non-secure read will return zero.

The DPPIC can subscribe to secure or non-secure channels through SUBSCRIBE_CHG[n] registers in order

to trigger task for enabling or disabling groups of channels. But an event from a non-secure channel will be

ignored if the group subscribing to this channel is secure. An event from a secure channel can trigger both

secure and non-secure tasks.

6.15.7 External domain access control

Other domains with their own CPUs can access peripherals, flash and RAM memories. The SPU allows

controlling accesses from those bus masters.

The external domains can access application MCU memories and peripherals. External domains are

assigned security attributes as described in register EXTDOMAIN[n].PERM.

Domain

Capability register

Permission register

LTE modem

Modem is always a non-secure

domain

Not applicable

Table 83: Register mapping for external domains

The figure below illustrates how the security control units are used to assign security attributes to

transfers initiated by the external domains:

4418_1315 v2.0

270

NRF9160-SICA-R7 Datasheet(PDF) 270 Page - Nordic Semiconductor