Datasheet

Functional overview STM32L052x6 STM32L052x8
28/143 DocID025936 Rev 8
3.10 Direct memory access (DMA)
The flexible 7-channel, general-purpose DMA is able to manage memory-to-memory,
peripheral-to-memory and memory-to-peripheral transfers. The DMA controller supports
circular buffer management, avoiding the generation of interrupts when the controller
reaches the end of the buffer.
Each channel is connected to dedicated hardware DMA requests, with software trigger
support for each channel. Configuration is done by software and transfer sizes between
source and destination are independent.
The DMA can be used with the main peripherals: SPI, I
2
C, USART, LPUART,
general-purpose timers, DAC, and ADC.
3.11 Analog-to-digital converter (ADC)
A native 12-bit, extended to 16-bit through hardware oversampling, analog-to-digital
converter is embedded into STM32L052x6/8 device. It has up to 16 external channels and 3
internal channels (temperature sensor, voltage reference). Three channels, PA0, PA4 and
PA5, are fast channels, while the others are standard channels.
The ADC performs conversions in single-shot or scan mode. In scan mode, automatic
conversion is performed on a selected group of analog inputs.
The ADC frequency is independent from the CPU frequency, allowing maximum sampling
rate of 1.14 MSPS even with a low CPU speed. The ADC consumption is low at all
frequencies (~25 µA at 10 kSPS, ~200 µA at 1MSPS). An auto-shutdown function
guarantees that the ADC is powered off except during the active conversion phase.
The ADC can be served by the DMA controller. It can operate from a supply voltage down to
1.65 V.
The ADC features a hardware oversampler up to 256 samples, this improves the resolution
to 16 bits (see AN2668).
An analog watchdog feature allows very precise monitoring of the converted voltage of one,
some or all scanned channels. An interrupt is generated when the converted voltage is
outside the programmed thresholds.
The events generated by the general-purpose timers (TIMx) can be internally connected to
the ADC start triggers, to allow the application to synchronize A/D conversions and timers.
3.12 Temperature sensor
The temperature sensor (T
SENSE
) generates a voltage V
SENSE
that varies linearly with
temperature.
The temperature sensor is internally connected to the ADC_IN18 input channel which is
used to convert the sensor output voltage into a digital value.
The sensor provides good linearity but it has to be calibrated to obtain good overall
accuracy of the temperature measurement. As the offset of the temperature sensor varies
from chip to chip due to process variation, the uncalibrated internal temperature sensor is
suitable for applications that detect temperature changes only.
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