Thinking about this more… (which is almost never a good thing with me): Cortex-M MCU manufacturers produce a file called system_xxxx.c (where xxx is the name of the mcu). There is a function in that file called SystemInit. Generally, this is something that should be called as early as possible and is called in the startup code. What I am now considering doing is adding our own version of “SystemInit” as I do not think it proper to modify the system_xxx.c module unless absolutely necessary.
To be more concise: * SystemInit() will still be called and will remain exactly the way it is now. * Add a function in hal_system.c (which is in hw/mcu) called hal_system_init(). * This function will be called by the startup code after SystemInit is called. * The configuration variable for DCDCEN will live in the MCU (default to 0) and will be overridden by any BSP that can support it. NOTE: I will comment on this in the hal_system_init() function, but this function will be called by both the bootloader and the app. If there is a case where doing something twice is undesirable that will have to be dealt with by anyone adding code to hal_system_init(). Comments? > On Apr 7, 2017, at 4:50 PM, Sterling Hughes > <sterling.hughes.pub...@gmail.com> wrote: > > Hi, > > Couple of thoughts: > > - I think this function/syscfg belongs in the MCU definition, as a > configuration item that can be controlled by the BSP. > > - I think it should be called as early as possible, so probably > hal_bsp_init(). > > - It’s a bid odd that hal_bsp_init() is the same for bootloader and running > image, we should probably have an option to make this different. I’d lean to > having more functionality in the image, because it’s upgradable. > > Sterling > > On 7 Apr 2017, at 16:32, will sanfilippo wrote: > >> Hello: >> >> I want to add some code that enables the DC/DC regulator for the nordic >> chips. Enabling this regulator reduces power consumption (considerably). For >> example, using the LDO when running from flash (cache enabled) is typically >> 7.4mA; using the DC/DC regulator it goes to 3.7 mA. >> >> It would be best to turn this on as soon as possible but it should only be >> enabled if there is some external circuitry attached to some of the pins >> (see the product specifications for more details). For all the BSP’s >> currently in the repo, the DC/DC regulator can (and should) be enabled. >> GIven that there is external circuitry involved I was going to create a >> syscfg variable that would either exist in the BSP or be overridden by the >> BSP. What I am having a bit of trouble figuring out is where should the code >> to enable the DC/DC regulator go? >> >> We have a choice of putting it in an existing place or doing something new. >> It seems to me that if we choose an exisiting place it would go in either >> hal_bsp_init() or hal_system_start(). >> >> Some comments about the existing functions: >> >> hal_system_start(): >> * Code would only need to be modified in one place (in hw/mcu). >> * This function is called after the bootloader does some work, so more power >> savings could be realized earlier on. >> * If you build an image with no bootloader I do not think this is called. >> * It might be a bit of an odd place to put this code (enabled the DC/DC >> regulator). >> >> hal_bsp_init(): >> * This is called early on by the bootloader. It is also called by the >> application which is a bit confusing to me. I am not super familiar with the >> bootloader but unless this function exists in some place I do not see or we >> override bsp syscfg variables in the bootloader app, hal_bsp_init() is going >> to do things twice. Is this true or am I missing something? >> * We would have to modify hal_bsp_init() in all the bsps. >> >> Honestly, I am not too concerned about having to modify all the bsps that >> use the nordic chip if the community thinks this code belongs in >> hal_bsp_init(). >> >> Any comments/suggestions? >> >> Thanks! >> >> PS If we decide that this code should exist in hw/mcu what I would do is to >> create a syscfg variable in hw/mcu/nordic (or hw/mcu/nordic/nrf52xxx and >> hw/mcu/nordic/nrf51xxx) called MCU_DCDC_ENABLE (or some such). By default, >> this will be 0. All the bsp syscfg.yml files will override this setting.
