STR91XF Datasheet, PDF (29/72 Pages) STMicroelectronics – ARM966E-S 16/32-Bit Flash MCU with Ethernet, USB, CAN, AC Motor Control, 4 Timers, ADC, RTC, DMA

STR91xF
Functional overview
2.24 A/D converter (ADC)
The STR91xF provides an eight-channel, 10-bit successive approximation analog-to-digital
converter. The ADC input pins are multiplexed with other functions on Port 4 as shown in
Table 2. Following are the major ADC features:
● Fast conversion time, as low as 2 usec
● Accuracy. Integral and differential non-linearity are both +/- 2 LSB (4 conversion counts).
● 0 to 3.6V input range. External reference voltage input pin (AVREF) available on 128-pin
packages for better accuracy on low-voltage inputs. The voltage on AVREF can range
from 1.0V to V_DDQ.
● CPU Firmware may convert one ADC input channel at a time, or it has the option to set the
ADC to automatically scan and convert all eight ADC input channels sequentially before
signalling an end-of-conversion
● Automatic continuous conversion mode is available for any number of designated ADC
input channels
● Analog watchdog mode provides automatic monitoring of any ADC input, comparing it
against two programmable voltage threshold values. The ADC unit will set a flag or it will
interrupt the CPU if the input voltage rises above the higher threshold, or drops below the
lower threshold.
● The ADC unit goes to stand-by mode (very low-current consumption) after any reset event.
CPU firmware may also command the ADC unit to stand-by mode at any time.
2.25 Standard timers (TIM) with DMA
The STR91xF has four independent, free-running 16-bit timer/counter modules designated
TIM0, TIM1, TIM2, and TIM3. Each general purpose timer/counter can be configured by
firmware for a variety of tasks including; pulse width and frequency measurement (input
capture), generation of waveforms (output compare and PWM), event counting, delay timing,
and up/down counting.
Each of the four timer units have the following features:
● 16-bit free running timer/counter
● Internal timer/counter clock source from a programmable 8-bit prescale of the CCU PCLK
clock output
● Optional external timer/counter clock source from pin P2.4 shared by TIM0/TIM1, and pin
P2.5 shared by TIM2/TIM3. Frequency of these external clocks must be at least 4 times
less the frequency of the internal CCU PCLK clock output
● Two dedicated 16-bit Input Capture registers for measuring up to two input signals. Input
Capture has programmable selection of input signal edge detection
● Two dedicated 16-bit Output Compare registers for generation up to two output signals
● PWM output generation with 16-bit resolution of both pulse width and frequency
● One pulse generation in response to an external event
● A dedicated interrupt to the CPU with five interrupt flags
2.25.1 DMA
A programmable DMA channel may be assigned by CPU firmware to service each timer/
counter module TIM0 and TIM1 for fast and direct transfers.
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