hi Philipp,
thanks a lot for that information! So it’s not even safe to always read low
byte first, and write high byte first for 16b SFRs!? That really sucks… :-(
Any idea where I can get a list of correct orders for the registers? Surely ST
has something like that…?
Georg I.
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 18 Apr 2014 12:29:56 +0200
> From: Philipp Klaus Krause <p...@spth.de>
> Subject: Re: [Sdcc-user] r/w order for STM8 16b registers
> To: sdcc-user@lists.sourceforge.net
> Message-ID: <5350fea4.2000...@spth.de>
> Content-Type: text/plain; charset=windows-1252
>
> Signierter PGP Teil
> Unfortunately, AFAIK, this is not the same for all 16-bit sfrs.
>
> In particular, some of the timer-related registers we always need to
> access the high byte first, followed by the low byte (both on reads
> and write):
>
> Examples from the STM8L101:
>
> For the TIM_CNTR register, the high byte must be read first, followed
> by the low byte.
>
> For the TIM_AAR register, the high byte must be written first,
> followed by the low byte.
>
> But I think it is only the timer registers that are high byte first.
>
> Philipp
>
> P.S.: If we can, we often want to read / write the low byte first,
> since ldw is faster than to ld, and ldw reads / writes the low byte first.
>
>
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