SNES Controller not detected

[emanuelelaface]

This is a bit weird issue. I spent some time developing a USB to DB9 (Commodore 64) controller using a SNES game pad. Everything worked well and because of the 2 Commodore 64 ports I decided to buy a second SNES controller, but this second is not even detected. Of course I thought that it could have been broken, but tested on a Mac it works perfectly. So I decided to open and inside the two controllers seems quite different. In particular the main difference that I can see is that one controller seems to have a crystal and the other not, but I can't see the chip used because it is under a black cap.

I am a bit stuck here because no message, appears on the console so it seems that the device is not detected in any way. Is there something that I can do to debug this issue?

[tobozo]

hi,

either one of the two controllers does not support USB-LS (may be limited to USB 2.0) or it's using a bad crystal and the esp32 can't compensate

comparing the details of the two controllers will tell about their capabilities; you'll need a tool like lsusb, on MacOS it is part of a packaged named usbutils

lsusb can be installed using brew:

$> brew install usbutils

... or using port:

$> sudo port install usbutils

run it once without arguments to find the VendorID:ProductID of the gamepads in the devices list:

$> lsusb

(...)
Bus 00x Device 00x: ID 0123:4567 Your Gamepad Controller 
Bus 00x Device 00x: ID 89ab:cdef Your Other Gamepad Controller 
(...)

then run lsusb with the VendorID/ProductID of that gamepad (e.g. 0123:4567 or 89ab:cdef)

$> lsusb -d 0123:4567 -v

copy the results in a text editor, rinse and repeat with the other gamepad, then compare both results

[emanuelelaface]

I report here the two output of lsusb, but they are very similar:

The diff between working and not working controllers:

2c2
< Bus 000 Device 003: ID 0810:e501
---
> Bus 000 Device 003: ID 081f:e401
11,12c11,12
<   idVendor           0x0810
<   idProduct          0xe501
---
>   idVendor           0x081f
>   idProduct          0xe401
45c45
<           wDescriptorLength      89
---
>           wDescriptorLength      98

The full output of working controller:

Bus 000 Device 003: ID 0810:e501
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.00
  bDeviceClass            0 [unknown]
  bDeviceSubClass         0 [unknown]
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x0810
  idProduct          0xe501
  bcdDevice            1.06
  iManufacturer           0
  iProduct                2
  iSerial                 0
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0022
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 [unknown]
      bInterfaceSubClass      0 [unknown]
      bInterfaceProtocol      0
      iInterface              0
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.10
          bCountryCode           33 US
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      89
          Report Descriptors:
            ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10
Device Status:     0x0000
  (Bus Powered)

The full output of not working controller:

Bus 000 Device 003: ID 081f:e401
Device Descriptor:
bLength                18
bDescriptorType         1
bcdUSB               1.00
bDeviceClass            0 [unknown]
bDeviceSubClass         0 [unknown]
bDeviceProtocol         0
bMaxPacketSize0         8
idVendor           0x081f
idProduct          0xe401
bcdDevice            1.06
iManufacturer           0
iProduct                2
iSerial                 0
bNumConfigurations      1
Configuration Descriptor:
  bLength                 9
  bDescriptorType         2
  wTotalLength       0x0022
  bNumInterfaces          1
  bConfigurationValue     1
  iConfiguration          0
  bmAttributes         0x80
    (Bus Powered)
  MaxPower              500mA
  Interface Descriptor:
    bLength                 9
    bDescriptorType         4
    bInterfaceNumber        0
    bAlternateSetting       0
    bNumEndpoints           1
    bInterfaceClass         3 [unknown]
    bInterfaceSubClass      0 [unknown]
    bInterfaceProtocol      0
    iInterface              0
      HID Device Descriptor:
        bLength                 9
        bDescriptorType        33
        bcdHID               1.10
        bCountryCode           33 US
        bNumDescriptors         1
        bDescriptorType        34 Report
        wDescriptorLength      98
        Report Descriptors:
          ** UNAVAILABLE **
    Endpoint Descriptor:
      bLength                 7
      bDescriptorType         5
      bEndpointAddress     0x81  EP 1 IN
      bmAttributes            3
        Transfer Type            Interrupt
        Synch Type               None
        Usage Type               Data
      wMaxPacketSize     0x0008  1x 8 bytes
      bInterval              10
Device Status:     0x0000
(Bus Powered)

[tobozo]

according to this both controllers are USB 1.0

bcdUSB               1.00

indeed some USB-LS devices with bad or no crystal can fail to be detected by ESP32-USB-Soft-Host, but this needs to be confirmed:

• slightly changing the voltage can affect the signal, is it powered by 5v exactly or is it using the VCC pin from the ESP?
• cable length can affect the signal, if possible confirm it also fails with shorter clip wires
• different port can give different results, ESP32-USB-Soft-Host supports up to 4
• further debugging requires an oscilloscope but this is beyond my knowledge and skills

[emanuelelaface]

Unfortunately none of the first three things made a difference. I tried both with VCC and +5V, I swapped ports (I enabled just 2 but) and tried with different cables.

I am available also to test with an oscilloscope but I do not know exactly what to test.

Thanks a lot for your help anyway.

[tobozo]

I am available also to test with an oscilloscope but I do not know exactly what to test.

you can verify that the bit rate / bit period are within the clock tolerance range (1.50±0.18 Mbit/s) in all 4 situations

if you feel adventurous you can also use wireshark + logic analyzer to compare data between working and failing scenarios i.e. to identify where the fail happens (voltage, handshake, setup, data, crc)

[emanuelelaface]

Thank you, I will check what I can do and see if I understand what is going on.