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Hello, |
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Your posts are kind of hard to reply to, sorry if I miss something. |
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I'll try to get everything into this message. |
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On Mon, Aug 7, 2017 at 10:41 AM, <tuxic@××××××.de> wrote: |
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> Hi, |
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> |
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> |
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> On 08/06 07:04, R0b0t1 wrote: |
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>> On Sun, Aug 6, 2017 at 11:50 AM, <tuxic@××××××.de> wrote: |
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>> > When I plug in such a little board into my PC, demesg |
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>> > reports: |
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>> > [ 1429.834140] usb 7-4: new low-speed USB device number 15 using ohci-pci |
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>> > [ 1429.965142] usb 7-4: device descriptor read/64, error -62 |
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>> > [ 1430.203151] usb 7-4: device descriptor read/64, error -62 |
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>> > [ 1430.438161] usb 7-4: new low-speed USB device number 16 using ohci-pci |
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>> > [ 1430.569151] usb 7-4: device descriptor read/64, error -62 |
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>> > [ 1430.803174] usb 7-4: device descriptor read/64, error -62 |
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>> > [ 1431.038184] usb 7-4: new low-speed USB device number 17 using ohci-pci |
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>> > [ 1431.456157] usb 7-4: device not accepting address 17, error -62 |
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>> > [ 1431.582204] usb 7-4: new low-speed USB device number 18 using ohci-pci |
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>> > [ 1432.000209] usb 7-4: device not accepting address 18, error -62 |
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>> > [ 1432.000244] usb usb7-port4: unable to enumerate USB device |
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>> > |
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>> |
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>> > |
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>> > My first thought was: The micronucleus bootloaed is missing or |
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>> > is defective... |
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>> > |
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>> > But plugging in the board into my Android tablet (the tablet runs |
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>> > Lollipop and is nothing special at all beside being rooted) via |
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>> > an OTG cable and using lsusb after that, it shows |
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>> > Bus 001 Device 003 ID 16d0:0753 MCS Digistump DigiSpark |
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>> > |
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>> |
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>> What the dmesg output is saying is that your USB hardware has reported |
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>> a communication error to the driver. It is my guess that the ATtiny85 |
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>> is not meeting the timing requirements for USB. |
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> |
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> The above is the only part of the dmesg log regarding this usb |
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> "device"... |
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> |
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> If I plug it into a usb-port, it "works"... (read: will be recognized |
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> according to dmesg, but still the udev rules dont get triggered, so |
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> I still get nothing under /dev/... |
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> |
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|
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You should look more closely at the dmesg output, though admittedly |
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some of this might not be obvious without reading the USB |
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specification. The computer being unable to read a descriptor or the |
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device failing to accept an address are things that will prevent the |
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device from properly registering on the bus. The initial handshake |
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fails to complete. |
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|
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> |
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>> Looking at the board there does not seem to be a crystal oscillator |
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>> which most people would consider necessary for doing USB |
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>> communication. This is an oversight on DigiStump's part and it is very |
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>> likely you will not be able to fix the communication issues. You |
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>> should contact them and tell them that your computer will not |
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>> recognize their device and that you suspect it is because the clock is |
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>> too inaccurate. |
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> |
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> ...the board is a thumbnail thing: |
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> http://digistump.com/products/1 |
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> |
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> No crystal. It is not an original digistum and had cost me less than 1 |
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> EUR...so not such a painful loss... |
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> |
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> |
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>> > |
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>> > What can I do to make this Digispark being correctly recognized? |
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>> > |
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>> > Thank you VERY much for any help in advance! |
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>> > |
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>> |
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>> Three things: |
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>> |
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>> 1) Return the one you bought and get a new one. The ATtiny85's |
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>> internal oscillator might be at the end of the bell curve but within |
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>> manufacturer tolerance, which isn't enough to produce a USB signal |
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>> close enough to the specified frequency. Expect the seller to pay for |
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>> return shipping. |
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> |
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> Returning the board does cost more than the board and I haven't |
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> any hope that this will change anything: I have six of them and none |
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> works. "The design can be improved..." to be friendly. |
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> |
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> |
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>> 2) You can calibrate the oscillator using instructions in this |
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>> application note: |
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>> http://www.atmel.com/Images/Atmel-2555-Internal-RC-Oscillator-Calibration-for-tinyAVR-and-megaAVR-Devices_ApplicationNote_AVR053.pdf. |
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>> This process still might not get you close enough. |
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> |
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> I have no oscilloscope nor a frequency counter. |
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> That is above my financial possibilities... |
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> |
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>> 3) Add a crystal oscillator to the ATtiny85 and change its fuses to |
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>> use the oscillator. You will need to recompile the firmware if the |
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>> crystal is a different frequency from the internal oscillator. |
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> |
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> There is not enough space on the board. |
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> |
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|
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Well, if you can't do any of those and if the board doesn't have level |
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shifters that might be affecting the signal then you probably won't be |
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able to use the board. If you send the hardware developer a message |
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that the board has failed to work with a device you will be doing them |
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a favor. |
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On Mon, Aug 7, 2017 at 10:51 AM, <tuxic@××××××.de> wrote: |
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> I ordered a similiar board yesterday, with a more reasonable setup: |
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> ATmega32u4 and a attached sdcard slot for the flash memory. |
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> The ATmega32u4 has a fully fledged USB 2.0 stack (is it called a "stack"?) |
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> and does not bitbang the whole stuff but "talks USB natively". |
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> I have gathered some hope so far, that this thingy will |
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> a) work with USB < 3.0 |
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> b) is more stable and more versatile |
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|
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The software is the stack, the device itself is said to have a USB |
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interface or peripheral. |
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The ATmega32U4 is a good choice but it can be exceedingly hard to use |
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without the Arduino wrappers. It's a good idea to learn how to use it, |
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but a lot of existing software you will find was personally very hard |
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to read, even after referring to the USB specification and doing a |
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bunch of searching. |
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Typically the suggestion is to avoid tinyAVRs (or microcontrollers of |
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similarly limited capabilities) for development work and only choose |
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them after you know what you are doing. If you have problems with the |
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ATmega32U4 you should get a board with, say, an ATmega328PA and use a |
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serial to USB converter for a while. |
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On another note, you should look up needle probes for multimeters and |
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oscilloscopes. You can also poke into insulated wires with them. |
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Working with SMD components isn't too hard, the solder tends to orient |
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them for you. For a lot of parts a hot air rework station is helpful |
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and is not too much money. If you are going to continue in this |
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direction you should get one as almost all modern parts come only in |
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SMD packages. Buying premade boards can only get you so far (but for |
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most people it's enough). |
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|
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R0b0t1. |
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