SAM4CM_14 Datasheet, PDF (977/1177 Pages) ATMEL Corporation – Atmel | SMART ARM-based Flash MCU

Figure 40-6. Non-optimized Temperature Conversion
ADC_CHSR[TEMP]= 1 and ADC_MR.TRGEN=1
Internal/External
Trigger event
(TRGSEL defined)
ADC_SEL
C T C T CT
CT CT
ADC_CDR[0]
C0
C1
C2
C3
C4
C5
ADC_CDR[TEMP]
ADC_LCDR
T0
T1
T2
T3
T4
T5
T0 C0 T1 ^C1 T2 C2 ^T3 C3 ^{T4 C4 T5}
Notes: ADC_SEL: Command to the ADC cell
C: Classic ADC Conversion Sequence
T: Temperature Sensor Channel
Assuming ADC_CHSR[0] = 1 and ADC_CHSR[TEMP] = 1
where TEMP is the index of the temperature sensor channel
trig.event1
DMA Buffer
Structure
trig.event2
trig.event3
0 ADC_CDR[0]
DMA Transfer
Base Address (BA)
0
ADC_CDR[TEMP]
BA + 0x02
0 ADC_CDR[0]
BA + 0x04
0 ADC_CDR[TEMP] ^{BA + 0x06}
0 ADC_CDR[0]
BA + 0x08
0
ADC_CDR[TEMP]
BA + 0x0A
The temperature factor has a slow variation rate and is potentially different from other conversion channels. As a
result, the ADC Controller triggers the measurement differently when TEMPON is set in ADC_TEMPMR but CH7
is not set in the ADC_CHSR.
Under these conditions, the measurement is triggered every second by means of an internal trigger generated by
the RTC, always enabled and totally independent of the internal/external triggers. The RTC event will be
processed on the next internal/external trigger event as described in Figure 40-7, "Optimized Temperature
Conversion Combined With Classical Conversions". The internal/external trigger is selected through the TRGSEL
field of ADC_MR.
In this mode of operation, the temperature sensor is only powered for a period of time covering the startup time
and conversion time (refer to Figure 40-8, "Temperature Conversion Only").
Every second, a conversion is scheduled for channel 7 but the result of the conversion is only uploaded in
ADC_CDR7 and not in ADC_LCDR. Therefore there is no change in the structure of the Peripheral DMA Controller
buffer due to the conversion of the temperature channel; only the enabled channels are kept in the buffer. The end
of conversion of the temperature channel is reported by means of EOC7 flag in ADC_ISR.
SAM4CM Series [DATASHEET]
Atmel-11203C-ATARM-SAM4CM32-SAM4CM16-SAM4CM8-Datasheet_06-Oct-14
977