Sound? #7
Replies: 3 comments 15 replies
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I've been thinking about that too. It is certainly possible, but this would involve both relatively extensive hardware and software changes. |
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what are some speakers I can order in germany to do tests? and where can I connect them, on the AUX? or GPIO (which could use PWM, right)? |
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Yes, all the GPIOs are PWM capable. You can even configure them using CVs or you can directly modify the source code which might be easier to be honest. You probably need to amplify your filtered PWM signal. |
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I've found this: https://www.austromodell.at/index.php?site=webshop&kategorie=152&anr=680&detail=1&farbe= which looks suitable, but to be honest I have no idea what I need to be able to connect the speaker to the decoder. assuming for the first tests I don't need an amplifier, what do I need to do to connect the speaker with 8ohm and 1W to the decoder? (of course I will come back with questions if I DO need to amplifiy the sound ;) ) |
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Can't really say much about the speaker to be honest.
You will not get 1 W out of the RP2040, directly loading the controller with the rather low impedance speaker will not work, i suggest reading Chapter 3.4 of this, which provides a good introduction into the topic and is a short read. If you delve deeper into the topic you will notice that there is some other things to worry about aswell, a clean power supply for example, provided non distorted sound is a priority. Also notice that there is also the option to use an external DAC IC as described in 3.4.2. which will probably the easier way to implement something like this. |
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Maybe it is outdated, but I just came across because I'm about to develop my own dcc decoder based on rp2040 too :) and so I was able to google this amazing project. I cannot say much about exactly this speaker, because there is no documentation on the linked website. But in a case of a regular speaker (which you can get for ~1€ or less) it will be red for +, black for -. Which means: + on a desired gpio for pwm, - on zero. In case with an amplifier it will be the same: For the test it will be even enough to use a regular headphone and connect pwm pin/amplifier output to l or r and ground correspondently. In case of a cheap speaker you will probably need to build low pass / high pass filters before the speaker. if it is about howto play an audio, the pico arduino sources are usable and have good examples. |
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Hi Gab-k, Questions: (out of scope) suggest to add dot/plus orientation on pcb. regards. |
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Hi Laurent, In order to realize a UART communication I would recommend you to look at the Raspberry Pi Pico uart examples . A simple UART communication should be relatively easy to implement, especially since you only have to send commands. The hello_uart example shows the simplest implementation, but you should keep in mind that the UART function is best called from core0, since the control algorithm runs on core1, which is time-critical. Gabriel |
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Hi Laurent. I also was unable to put together the BOM. The parts were not being... auto detected? for lack of a better term, on JLCPCB. I would have to know much more about the parts and parameters required. I'm only a software engineer, never hardware so out of my wheelhouse unfortunately. I have had some boards printed for another project but they didn't require any surface mount parts (and the files were all ready to be uploaded into JLCPCB), it seems there is considerable additional complexity in producing these files. If you are still interested, there is now someone selling some slightly modified boards put together already here: https://ilabs.se/product/opendec02/ |
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Hi! I also had issues with the BOM (I'm also more a software-guy than hardware), but with the excellent help from Gabriel I was able to order fully assembled boards. Because I also had issues Gabriel provided some additional files here: #6 hope that helps. -Kai |
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HI Gabriel,
thank's for your reply.
I look at your link.
I well know teensyduino, but I code them via IDE which seem a bit more simple.
I know regulation , normaly you should use a time sample of around 0.1s-0.25s for PID regulator.
Due to lag you may have an othershoot.
As me no need to feedforward in this case of speed control...
Have you ever see a train with constante speed when it climbed ? seem not ;o)...
I don't have any dcc train so maybe I'am wrong...
thank's a lot.
Laurent.
…----- Mail original -----
De: "Gabriel Koppenstein" ***@***.***>
À: "gab-k/RP2040-Decoder" ***@***.***>
Cc: "LaurentDelaon" ***@***.***>, "Comment" ***@***.***>
Envoyé: Lundi 14 Août 2023 21:00:25
Objet: Re: [gab-k/RP2040-Decoder] Sound? (Discussion #7)
Hi Laurent,
In order to realize a UART communication I would recommend you to look at the Raspberry Pi Pico uart examples . A simple UART communication should be relatively easy to implement, especially since you only have to send commands. The hello_uart example shows the simplest implementation, but you should keep in mind that the UART function is best called from core0, since the control algorithm runs on core1, which is time-critical.
Gabriel
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Love what you've done.
I was wondering if you think it would be possible to make a version of this with sound output?
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