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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!2.eu.feeder.erje.net!feeder.erje.net!news.mb-net.net!open-news-network.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: The Natural Philosopher Newsgroups: sci.electronics.design,comp.sys.raspberry-pi Subject: Re: uP port mapping Date: Fri, 13 Sep 2024 09:36:31 +0100 Organization: A little, after lunch Lines: 44 Message-ID: References: <6jg6ejlh6f0iqo84v2dlo4487fpccprjmh@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 13 Sep 2024 10:36:31 +0200 (CEST) Injection-Info: dont-email.me; posting-host="8bcbd3f8d2f4cbc06f602d76aec253f3"; logging-data="817958"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX189wfyfYn1dYoDgIWoCfQk9ofGkd6JcGPg=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:Re/1EjzXKQKcJSARhYBEMviYzM4= Content-Language: en-GB In-Reply-To: Bytes: 3136 On 12/09/2024 22:28, Theo wrote: > In comp.sys.raspberry-pi john larkin wrote: >> RP2040 has I think 2 PIO blocks and each has a couple of hardware >> programmable state machines, and those can be set up to drive pins. >> I'm mostly concerned now with a PCB schematic design, picking the >> appropriate and easy-to-route pins from the CPU to things. >> >> My general question, for various processors, is how to associate bits >> in integer variables with physical pins on the chip. > > This is the function of a 'pinmux'. Different chips have different > capabilities of the pinmux, but it's rare to be able to connect any GPIO to > any pin - that's more FPGA territory. Typically the pinmux is just about > selecting one of multiple fixed functions for a given pin > (SPI1_MISO/I2C3_SDA/UART2_TX/...) > That is my understanding, too. What the pins do is programmable, but not tire mappings to specific registers inside the processor > So either you route your DAC to consecutive pins (D0 to GPIOn, D1 to n+1, > ..., ideally where n is a multiple of 8), or you're prepared to do the > necessary bit shuffling in software (which can be slow and non-atomic). I'd > suggest sticking to consecutive ordering if you can. > Yes. > (although I have no experience of the RP2xxx GPIO/PIO shenanigans) > I have - a very very little - but I have spent some time reading the docs to see at least if the Pi PICO is suitable for various speculative projects or not. There is a massive amount of shit it *can* do that probably only one person in a hundred would ever use. It just so happens that driving parallel connected external logic is something I have an interest in, so I read that bit... :-) > Theo -- Civilization exists by geological consent, subject to change without notice. – Will Durant