3.3V limitation #3
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Hello again, First of all, hope there have been updates, as I see this repo hasn’t been updated in months… I took note of the 3.3V limitation for this project at this time, and since I see no updates about support for 5V, which apparently goes for most Roland synths, I feel it best to ask: since the official SRX cards do support 5V, is it possible to rewrite one of those cards in the meantime? I noted that 5V isn’t supported due to the modern components needed for a new card, so surely using old ones are an adequate workaround for now? I already have an XV3080 and two SRX cards for testing if this is an option. Thanks again in advance. |
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Replies: 8 comments 16 replies
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Addendum: partially but not solely because of this project, I'm considering selling my XV-3080 in favor of an XV-5050. That said, if I read the service notes correctly, the switch to 3.3V may have started as early as that unit. The internal mask ROM's definitely use the same series of chips as the known-to-work Fantom XR. Since I'm pretty sure the 5050 is also Roland's first synth to support only SRX and not SR-JV, there is a chance that the 5V aspect would only be important both for general conformance and in order to work in the earliest two SRX synths, namely, the 3080 and 5080, and part of me thinks it's related to the fact that both models DO support SR-JV80 ROM's as well. Attached is a screenshot from said 5050 service notes. 
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Yes, supporting 5V is important. I do have a XV5080 as well purchased for testing purposes. I want to do this at some point and I have looked into it somewhat, but what I need is a bit of circuitry allowing both voltages from a single pin that I don't know yet exactly how it works (basic electronic design is something I have picked up along the way, self taught). Something along the lines of a zener diode with a low breakdown voltage and small p-channel mosfets for switching between 3.3V and 5.V I think. Just putting LDOs and voltge levelers for the address and data pins on the cards for a specific 5V version won't help as the programmer is designed for 3.3V and in my opinion, it doesn't make sense to have two programmers with differing programmer firmwares. That would make things too complicated. At the moment, other projects have taken over priority unfortunately. I might pick up on this in a few months. About the 5050: on page 24 of the services notes (Circuit Diagram (Main 4/7)), there are the CN6 and CN7 connectors in more detail on the right hand side. Yes, it seems to be 3.3V for the main flash ICs. The 5V only go into that secondary microwire flash eeprom (Microchip 93LC46 I think I read my notes from earlier correctly) of which I still don't know what it's even used for. I have dumped like two of those and they were always empty. As a result, I haven't even bothered to solder them onto my card and it still works perfectly. |
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Thanks for the response, first of all. Was nervous you were so caught up with the other matters you mention that I’d need to wait longer. The explanation about the voltages does make sense, and it’s a shame that the programmer only supports 3.3V too. Does that mean it’ll have the same effect if I use an official SRX board instead? That was the question I was originally asking in a roundabout way. |
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Ah, no, you cannot use original SRX boards and reprogram them. The reason is that there is a write protect pin on the flash ICs that isn't wired to the JAE connector that connects the SRX card to the mainboard of the synth. My boards and programmers have a secondary connector on them that allows to set this write protect pin to on or off. As a result, the original SRX cards are always write protected.
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Ah, thanks for clarifying. All the more reason to save up for a 5050, or at least trade my 3080 for one, for now then. |
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Patiently waiting for 5V version as well. Just can't justify buying XR unit those days, already have 5080 and 2020. Hope, you'll have some time to work on that. I'm totally fine if it's a separate programmer for 5V logic and 5V card version won't support 3.3V operation. |
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To the list of host devices here, like the Fantom-XR which uses 3.3V for the SRX, I would like to add the "SonicCell". I have both and have measured them. |
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Hello, I am also the owner of a XV-3080. Thank you for your work which is really interesting and useful! After a glance at the service manual (available here for example), I am pretty sure that the SRX slots in the 3080 are also 3.3 V and not 5 V (except the serial EEPROM):
Compared to the Fantom-XR, the only difference I can see is that pins 37/39 are 5 V on the XV-3080 instead of 3.3 V (they seem to be used only for the serial EEPROM). Therefore, may I suggest that you just cut traces from pins 37/39 while leaving the EEPROM unpopulated, and test your board with this configuration? It should be harmful neither for the expansion carrier board nor for the SRX board. As a bonus, if you have access to an original SRX board, and confirm that pins 37/39 only go to the EEPROM, you may want to route them to a separate supply rail for it (if there is a case where the EEPROM is actually used - not certain). The EEPROM should then work whatever the supply voltage. |
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Yes, I have an SRX-01 board. I installed it in a "SonicCell" to measure the voltage at pins 37/39 of the "JAE" connector. The voltage also measured 3.3 volts. As for the serial EPROM, it most likely contains information about patch names and numbers, depending on the host device the SRX extension is installed on, It doesn't look the same. Here's a visual example with the "SRX-03 Studio" : |
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When I speculated about the contents of the serial EPROM, I meant only the small portion that differs in name mapping between host devices, not the entire large portion of the table, which is displayed identically on all hosts. Documents from reverse engineering enthusiasts explicitly point to the theoretical unknowns of some WAVE ROM sections..., although physical reverse engineering is already making considerable progress. |
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Thank you for the clarification. I may have been misled by the fact that the pictures show that none of the serial EEPROMs are fitted and mentioned in the BOM. BTW, srxtool does not seem to dump any of these EEPROMs. |
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Unfortunately, while I am indeed the maintainer of custom SR-JV80 ROM creation tools and can also say there's significant overlap in data with the SRX ROM's, I've not tried messing with physical SRX boards and thus can't say what the purpose of them is. However, this document from someone else, which was what inspired me to pursue the SRJV authoring project, suggests that the patches actually are embedded in the wave ROM's like for the SRJV series. Then again, I'm pretty sure the author was using an Integra-7 SD card as a basis for his findings, judging from some of the rest of the document. |
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Sorry for the delay due to my workload. |
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I likely won't update this repo any more except for linking to your repository if turns out to work better. Feel free to fork. The only "limitation" imposed by the strongly reciprocal CERN license is that you cannot make modifications to the design and sell the boards without making the modifications open under the same license again. It's one of the things that annoyed me by people making use of open source designs for business and not sharing their improvements. |
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Thank you very much for your enthusiasm and willingness to continue the project in a fork. I look forward to your improvements to OpenSRX. If I feel I can help in any way, I'll definitely join the discussions. |
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Thank you very much for your SR-JV project, for your good work, and for your curiosity and enthusiasm for OpenSRX. Let me ask: have you sorted out the patch tables (in your SR-JV project) yet? |
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Well, I think the project is already viable as is. My job leaves me hardly any time, but I am open to any interesting ideas to enhance the project. |
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Like I said at the end of the message you were referring to, I haven't cracked the patch table code for the SRX ROM's, and from what I do know, I'm not sure if anyone else has at this time, either....as for SRJV ROM's, those are more trivial mainly because no encryption is involved, and I only know of three different synth/types of patches that those ROM's support, all of which I've already figured out. Silver lining: the updates for this project means I might make one openSRX card for my XV0308, so I might be able to do some research that way. |
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The only change I had to make was to the kicad folder. I created the fork, but I am sending a pull request, so that everything can be shared from your repo (if you like to do so). |
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Could you send me a private message somewhere? Seeing as we both seem to be committed to this idea, I suppose it might be time we collaborate, especially since, truth be told, I don't have the soldering skills to make my own programmer for these yet. |
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If this request was also directed to me, is the contact page in your site the best way to get in touch? |
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Yes and yes. Also, that's not my website. |
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Refer to this regarding who I was speaking to.. That being said, if you do make some code changes that you feel are worth sharing, by all means, link a fork to me, or better yet, submit a pull request, and we can discuss then. In the meantime, I realize now I'm overdue for closing this issue, as even if rperdriau hadn't addressed it, we should probably refrain from too much spamming of the original repo owner's notifications. |
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Ah, no, you cannot use original SRX boards and reprogram them. The reason is that there is a write protect pin on the flash ICs that isn't wired to the JAE connector that connects the SRX card to the mainboard of the synth. My boards and programmers have a secondary connector on them that allows to set this write protect pin to on or off. As a result, the original SRX cards are always write protected.