NRF52811-QCAA-R datasheet(263/444 Pages) NORDIC

263 / 444 page

Peripherals

In this mode, the RESULTDONE event signals has the same meaning as DONE when no oversampling

takes place. Note that both events may occur before the actual values have been transferred into RAM by

EasyDMA.

Example of RAM placement (even RESULT.MAXCNT), channels 1, 2 and 5 enabled on page 263 provides

an example of results placement in Data RAM, with an even RESULT.MAXCNT. In this example, channels 1,

2 and 5 are enabled, all others are disabled.

(…)

CH[2] 1st result

CH[1] 1st result

RESULT.PTR

16 15

RESULT.PTR + 4

CH[1] 2nd result

CH[5] 1st result

CH[5] 2nd result

CH[2] 2nd result

RESULT.PTR + 8

CH[5] last result

CH[2] last result

RESULT.PTR +

2*(RESULT.MAXCNT – 2)

Figure 105: Example of RAM placement (even RESULT.MAXCNT), channels 1, 2 and 5 enabled

Example of RAM placement (odd RESULT.MAXCNT), channels 1, 2 and 5 enabled on page 263 provides

an example of results placement in Data RAM, with an odd RESULT.MAXCNT. In this example, channels 1, 2

and 5 are enabled, all others are disabled. The last 32-bit word is populated only with one 16-bit result.

(…)

CH[2] 1st result

CH[1] 1st result

RESULT.PTR

16 15

RESULT.PTR + 4

CH[1] 2nd result

CH[5] 1st result

CH[5] 2nd result

CH[2] 2nd result

RESULT.PTR + 8

CH[5] last result

RESULT.PTR +

2*(RESULT.MAXCNT – 1)

Figure 106: Example of RAM placement (odd RESULT.MAXCNT), channels 1, 2 and 5 enabled

6.17.6 EasyDMA

After configuring RESULT.PTR and RESULT.MAXCNT, the ADC resources are started by triggering the START

task. The ADC is using EasyDMA to store results in a Result buffer in RAM.

The Result buffer is located at the address specified in the RESULT.PTR register. The RESULT.PTR register

is double-buffered and it can be updated and prepared for the next START task immediately after the

STARTED event is generated. The size of the Result buffer is specified in the RESULT.MAXCNT register

and the ADC will generate an END event when it has filled up the Result buffer, see ADC on page 264.

Results are stored in little-endian byte order in Data RAM. Every sample will be sign extended to 16 bit

before stored in the Result buffer.

The ADC is stopped by triggering the STOP task. The STOP task will terminate an ongoing sampling. The

ADC will generate a STOPPED event when it has stopped. If the ADC is already stopped when the STOP task

is triggered, the STOPPED event will still be generated.

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