Clock frequency reduced about 1 second after configuration

I synthesized the blinking led example given here.
When I download the bitstream in SRAM the design works during about 1 seconds as expected. But after this time, the frequency is reduced and the design works about 10 times slower.

Is it a known bug ?

Hello,
Nobody have similar problem ?
I tryed with new design (in chisel) that I publied here. Platform pinout is given here.

And I probed the pin XI of CH552 (pin 17). I can measure correct frequency during about 1-2 seconds then the quartz shutdown suddenly.

Is there a bug in CH552 ? Does anybody else have similar problem ?

Thanks

I configured the fpga with this github project..
I have image on the screen but with some kind of “flicker” like seen on this video..

If I measure XTAL_IN with scope when I configure it I have this waveform :

The 24Mhz during the configuration, and 5 seconds of 24Mhz of oscillation then ~300mv with no more oscillation. But screen works … with flicker.

Ok it’s seems to be my USB host port ! I tested the flashed design on a simple USB power wall and the bug disapear.
I will test on other computer.

1 Like

the pre burn firmware is buggy, timing constraint is break, you need check the adder timing constraint

Hi @zepan, can you give a link on a tutorial to “check the adder timing constraint” ?
And how to flash an up to date firmware in CH552 ?
Thanks

oh, I’m not mean the 552’s firmware, but fpga’s firmware.

you can write your blink project, and check the timing constraint

But, the blink project is yours from sipeed github.
And all designs I configure on longan nano has the same problem, but only on my ThinkPad T430 USB ports.

It’s definitely CH552 problem or maybe a driver on my computer ?

I just tested the board with an USB selfpowered hub. If I left hub powered in standalone and plug the Tang Nano on it -> it’s blinking correctly.
But, if I plug the Hub on my computer, the led stop blinking.

My dmesg trace is following when I plug the hub (with Tang Nano plugged on it) on computer :

$ sudo dmesg -c
[118726.525523] usb 1-2: new high-speed USB device number 48 using xhci_hcd
[118726.673604] usb 1-2: New USB device found, idVendor=045b, idProduct=0209, bcdDevice= 1.00
[118726.673609] usb 1-2: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[118726.674354] hub 1-2:1.0: USB hub found
[118726.674401] hub 1-2:1.0: 4 ports detected
[118726.961072] usb 1-2.1: new high-speed USB device number 49 using xhci_hcd
[118727.061204] usb 1-2.1: New USB device found, idVendor=045b, idProduct=0209, bcdDevice= 1.00
[118727.061208] usb 1-2.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[118727.061633] hub 1-2.1:1.0: USB hub found
[118727.061662] hub 1-2.1:1.0: 4 ports detected
[118727.144888] usb 1-2.4: new full-speed USB device number 50 using xhci_hcd
[118727.252311] usb 1-2.4: New USB device found, idVendor=0403, idProduct=6010, bcdDevice= 5.00
[118727.252316] usb 1-2.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[118727.252319] usb 1-2.4: Product: Sipeed-Debug
[118727.252321] usb 1-2.4: Manufacturer: Kongou Hikari
[118727.252323] usb 1-2.4: SerialNumber: 85522A1A47
[118727.261940] ftdi_sio 1-2.4:1.0: FTDI USB Serial Device converter detected
[118727.261979] usb 1-2.4: Detected FT2232C
[118727.262334] usb 1-2.4: FTDI USB Serial Device converter now attached to ttyUSB0
[118727.262481] ftdi_sio 1-2.4:1.1: FTDI USB Serial Device converter detected
[118727.262527] usb 1-2.4: Detected FT2232C
[118727.262863] usb 1-2.4: FTDI USB Serial Device converter now attached to ttyUSB1