1. Documentation conventions

1.1 General information

The STM32L0x1 devices have an Arm ®(a) Cortex ® -M0+ core.

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1.2 List of abbreviations for registers

The following abbreviations (b) are used in register descriptions:

read/write (rw)Software can read and write to this bit.
read-only (r)Software can only read this bit.
write-only (w)Software can only write to this bit. Reading this bit returns the reset value.
read/clear write0 (rc_w0)Software can read as well as clear this bit by writing 0. Writing 1 has no effect on the bit value.
read/clear write1 (rc_w1)Software can read as well as clear this bit by writing 1. Writing 0 has no effect on the bit value.
read/clear write (rc_w)Software can read as well as clear this bit by writing to the register. The value written to this bit is not important.
read/clear by read (rc_r)Software can read this bit. Reading this bit automatically clears it to 0. Writing this bit has no effect on the bit value.
read/set by read (rs_r)Software can read this bit. Reading this bit automatically sets it to 1. Writing this bit has no effect on the bit value.
read/set (rs)Software can read as well as set this bit. Writing 0 has no effect on the bit value.
read/write once (rwo)Software can only write once to this bit and can also read it at any time. Only a reset can return the bit to its reset value.
toggle (t)The software can toggle this bit by writing 1. Writing 0 has no effect.
read-only write trigger (rt_w1)Software can read this bit. Writing 1 triggers an event but has no effect on the bit value.
Reserved (Res.)Reserved bit, must be kept at reset value.

a. Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

b. This is an exhaustive list of all abbreviations applicable to STMicroelectronics microcontrollers, some of them may not be used in the current document.

1.3 Glossary

This section gives a brief definition of acronyms and abbreviations used in this document:

1.4 Availability of peripherals

For availability of peripherals and their number across all sales types, refer to the particular device datasheet.

1.5 Product category definition

Table 1 gives an overview of memory density versus product line.

The present reference manual describes the superset of features for each product line, Refer to Table 2 for the list of features per category.

Table 1. STM32L0x1 memory density
Memory densityCategory 1Category 2Category 3Category 5
8 KbytesSTM32L011x
STM32L021x (AES)
---
16 KbytesSTM32L011x
STM32L021x (AES)
STM32L031x
STM32L041x (AES)
--
32 Kbytes-STM32L031x
STM32L041x (AES)
STM32L051x-
64 Kbytes--STM32L051xSTM32L071x
128 Kbytes---STM32L071x
STM32L081x (AES)
192 Kbytes---STM32L071x
STM32L081x (AES)
Table 2. Overview of features per category
FeatureCategory 1Category 2Category 3Category 5
MPU--full-featuredfull-featured
NVMfull-featured,
single bank
full-
featured,
single bank
full-
featured,
single bank
full-featured
Cyclic redundancy check calculation unit (CRC)full-featuredfull-featuredfull-featuredfull-featured
Firewall (FW)--full-featuredfull-featured
Power control (PWR)full-featuredfull-featuredfull-featuredfull-featured
Reset and clock control (RCC)HSE supports
bypass only, no
CSS on HSE
full-featuredfull-featuredfull-featured
GPIOAfull-featuredfull-featuredfull-featuredfull-featured
GPIOB[0:9],
BOOT0/PB9
sharing the
same pin
full-featuredfull-featuredfull-featured
GPIOC[14:15][0][13:15]full-featuredfull-featured
GPIOD--[2]full-featured
GPIOE---full-featured
GPIOH-[0:1][0:1][0:1][9:10]
System configuration controller (SYSCFG)full-featuredfull-featuredfull-featuredfull-featured
Direct memory access controller (DMA1)full-featuredfull-featuredfull-featuredfull-featured
Nested vectored interrupt controller (NVIC)full-featuredfull-featuredfull-featuredfull-featured
Extended interrupt and event controller (EXTI)full-featuredfull-featuredfull-featuredfull-featured
Analog-to-digital converter (ADC1)full-featuredfull-featuredfull-featuredfull-featured

Table 2. Overview of features per category (continued)

FeatureCategory 1Category 2Category 3Category 5
Comparator (COMP1)full-featuredfull-featuredfull-featuredfull-featured
Comparator (COMP2)full-featuredfull-featuredfull-featuredfull-featured
Advanced encryption standard hardware accelerator (AES)full-featuredfull-featured-full-featured
General-purpose timers (TIM2)full-featuredfull-featuredfull-featuredfull-featured
General-purpose timers (TIM3)---full-featured
General-purpose timers (TIM21)full-featuredfull-featuredfull-featuredfull-featured
General-purpose timers (TIM22)-full-featuredfull-featuredfull-featured
Basic timers (TIM6)--full-featuredfull-featured
Basic timers (TIM7)---full-featured
Low power timer (LPTIM1)full-featuredfull-featuredfull-featuredfull-featured
Independent watchdog (IWDG)full-featuredfull-featuredfull-featuredfull-featured
System window watchdog (WWDG)full-featuredfull-featuredfull-featuredfull-featured
Real-time clock (RTC)full-featuredfull-featuredfull-featuredfull-featured
Inter-integrated circuit (I2C1) interfacefull-featuredfull-featuredfull-featuredfull-featured
Inter-integrated circuit (I2C2) interface--full-featuredfull-featured
Inter-integrated circuit (I2C3) interface---full-featured
Universal synchronous asynchronous receiver transmitter (USART1)--full-featuredfull-featured
Universal synchronous asynchronous receiver transmitter (USART2)no synchronous mode,
no LIN mode,
no dual clock,
no receiver timeout,
no ModBus,
no autobaudrate
full-featuredfull-featuredfull-featured
Universal synchronous asynchronous receiver transmitter (USART4)---full-featured
Universal synchronous asynchronous receiver transmitter (USART5)---full-featured
Low-power universal asynchronous receiver transmitter (LPUART1)full-featuredfull-featuredfull-featuredfull-featured
Serial peripheral interface(SPI1)full-featuredfull-featuredfull-featuredfull-featured
Serial peripheral interface/ inter-IC sound (SPI2/I2S2)--full-featuredfull-featured
Debug support (DBG)full-featuredfull-featuredfull-featuredfull-featured
Device electronic signaturefull-featuredfull-featuredfull-featuredfull-featured