OPAMP1 in STM32L151 how to turn on ?

[Mikhail Polyakov]

Posted on January 17, 2013 at 06:15

Hello  everybody !

How to turn on OPAMP1 in STM32L151 ?Under debug (I use Keil + Ulink)   I see the content of OPAMP_CSR register.  All bits are 0 after the reset of the processor.  But according to datasheet, after reset some bits must be 1.When I try to set any bit to 1 , it stay at 0.OPAMP1 behaves as if this peripheral is switched off or clocking of this peripheral is switched off.  But there is no bits related to OPAMP in RCC.What am i do wrong ?  How to turn on  OPAMP1 ? #opamp-opamp1-stm32l151-turn-on

[lowpowermcu]

Posted on January 17, 2013 at 09:15

Hi

Just look at the header of opamp.c driver the steps are described there:  (#) COMP AHB clock must be enabled to get write access        to OPAMP registers using        RCC_APB1PeriphClockCmd(RCC_APB1Periph_COMP, ENABLE)     (#) Configure the corresponding GPIO to OPAMPx INP, OPAMPx_INN (if used)        and OPAMPx_OUT in analog mode.     (#) Configure (close/open) the OPAMP switches using OPAMP_SwitchCmd()

(#) Enable the OPAMP peripheral using OPAMP_Cmd()

MCU Lüfter

[Mikhail Polyakov]

Posted on January 17, 2013 at 10:30

Thank You  for answer.

I do not use any libraries, I write all registers myself.So I have no file  opamp.c  If You have it, please post it here, i Will look.Accordance with Your recomendations I have turn on COMP AHB clock,but behavior of  OPAMP CSR registor did  not change. In datasheet I can not find anything about switching on COMP AHB clock  before use OPAMP.  

[lowpowermcu]

Posted on January 17, 2013 at 10:41

Hi,

You find it here

http://www.st.com/internet/com/SOFTWARE_RESOURCES/SW_COMPONENT/FIRMWARE/stm32l1_stdperiph_lib.zip

with examples on OPAMPs in STM32L1xx_StdPeriph_Lib_V1.1.1\Project\STM32L1xx_StdPeriph_Examples\OPAMP\ and opamp.c in STM32L1xx_StdPeriph_Lib_V1.1.1\Libraries\STM32L1xx_StdPeriph_Driver\src\In datasheet I can not find anything about switching on COMP AHB clock  before use OPAMP.   >> You should look in the reference manual available here:

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/CD00240193.pdf