Adc Functional Description; Calibration (Adcal); Figure 22. Adc Block Diagram - STMicroelectronics STM32F05 series Reference Manual

RM0091
12.4

ADC functional description

Figure 22

Figure 22. ADC block diagram

ADC_IN[15:0]
TIM1_TRGO
TIM1_CC4
TIM2_TRGO
TIM3_TRGO
TIM15_TRGO
12.4.1

Calibration (ADCAL)

The ADC has a calibration feature. During the procedure, the ADC calculates a calibration
factor which is internally applied to the ADC until the next ADC power-off. The application
must not use the ADC during calibration and must wait until it is complete.
Calibration should be performed before starting A/D conversion. It removes the offset error
which may vary from chip to chip due to process variation.
The calibration is initiated by software by setting bit ADCAL=1. Calibration can only be
initiated when the ADC is disabled (when ADEN=0). ADCAL bit stays at 1 during all the
calibration sequence. It is then cleared by hardware as soon the calibration completes. After
this, the calibration factor can be read from the ADC_DR register (from bits 6 to 0).
The calibration factor is kept if the ADC is disabled (ADEN=0). However, if the ADC is
disabled for extended periods, then it is recommended that a new calibration cycle is run
before re-enabling the ADC.
The calibration factor is lost each time power is removed from the ADC (for example when
the product enters STANDBY or VBAT mode).
shows the ADC block diagram and
SCANDIR
up/down
ADEN/ADDIS
CH_SEL[18:0]
CONT
singe/cont
V
BAT
Input
V
REF
Selection &
T
S Scan Control
SMP[2:0]
analog input
sampling time
channels
Start & Stop
Control
AUTDLY
auto-delayed conv
ADSTART
s/w trigger
ADSTP
stop conv
EXTEN[1:0]
trigger enable
and edge selection
EXTSEL[2:0]
trigger selection
Doc ID 018940 Rev 1
Table 30
≥ V
V
DDA DD
Analog Supply
2.4V to 3.6
AUTOFF
auto-off mode
Supply and
ADCAL
reference
self calibration
SAR ADC
Vin
CONVERTED DATA
start
OVRMOD
overrun mode
ALIGN
left/right
RES[1:0]
12,10,8,bts
JOFFSETx[11:0]
JOFFSETx_CH[11:0]
h/w
trigger
DISCEN
discontinuous
mode
Analog-to-digital converter (ADC)
gives the ADC pin description.
AREADY
EOSMP
ADC Interrupt
EOSEQ
EOC
OVR
AWD
DATA[11:0]
AHB
TO
APB
APB
interface
DMAEN
DMACFG
AWDxEN
AWDxSGL
AWDCHx[4:0]
LTx[11:0]
HTx[11:0]
CPU
IRQ
master
A
H
slave
B
DMA
master
DMA request
AWDx
Analog
watchdog
171/742