USB-USB: suspend/wake support for keyboard
tmk opened this issue · 4 comments
Problem
The converter does not support to suspend a keyboard. MAX3421E and keyboard keep drawing power while computer is sleeping.
TODO
- Add suspend and wake support to USB_Host_Shield_2.0
- Add retmote wakeup support to USB_Host_Shield_2.0
- Converter suspends a keyboard while sleeping
- MAX3421E power saving
MAX3421e RWUIRQ issue
Seemingly RWUIRQ is not triggered with remote wakeup from some devices. This seems to depend on remote wake implementation and singnal term(1-15ms).
RWUIRQ does not work with:
- TMK Alps64(LUFA) - full speed
- HHKB Classic - full speed
- Realforce RGB - full speed
OK with:
- VARMILO MA109C - full speed
- Cherry G80-3600 - low speed
- ThinkPad keyboard 55Y9053 - low speed
- Poker X - low speed
https://electronics.stackexchange.com/questions/372236/bugs-in-maxim-chip-max3421e-used-as-usb-host
WORK AROUND
Check bus state using SAMPLEBUS and detect remote wakeup signal when bus is K state.
This does not detect remote wakeup signal every time. This can miss it and you will have to hold a key a while or press several times in that case.
// sample bus
regWr(rHCTL, bmSAMPLEBUS);
while(!(regRd(rHCTL) & bmSAMPLEBUS));
uint8_t bus_sample;
bus_sample = regRd(rHRSL);
bus_sample &= (bmJSTATUS | bmKSTATUS);
if (bus_sample == bmKSTATUS) {
// K-state means remote wakeup when suspended
}
DEVICE_REMOTE_WAKEUP
To enable Remote Wakeup on a device/keyboard
we need to send SET_FEATURE request using ctrlReq() :
// SET_FEATURE(DEVICE_REMOTE_WAKEUP)
rcode = pUsb->ctrlReq(bAddress,
0, // End Point: 0
(USB_SETUP_HOST_TO_DEVICE | USB_SETUP_TYPE_STANDARD | USB_SETUP_RECIPIENT_DEVICE), // bmRequestType
USB_REQUEST_SET_FEATURE, // bRequest
USB_FEATURE_DEVICE_REMOTE_WAKEUP, 0, // wValue
0, // wIndex
0, 0, NULL, NULL); // wLength
USBTRACE2("RWU: ", rcode);
Power Saving
Even in host mode MAX3421E can enter into low-power state using PWRDOWN bit,
though document says:
This bit is designed only for peripheral mode usage, although it is accessible in host mode. The
CPU should never set POWERDOWN = 1 when operating as a host.
In low-power state the chip cannot detect and handle any USB events such like remote wakeup, attach and detach. You will have to enumerate and intialize a device after putting out of low-power state.
When enabling remote wakeup we cannot put the chip into the low-power state.
Current the converter draws while in "configured"
around 22.3mA in active state
Current the converter draws while in "suspended"
when Remote Wakeup is enabled
The converter draws around 7.8mA(without keyboard) or 8.2mA(with keyboard).
MAX3421 is powered up.
when Remote Wakeup is disabled
The converter draws around 0.1mA.
MAX3421 is powered down.