[USB Host] Keyboard Output Report - How to control the 3 LEDs? (NumLock, Caps Lock and Scroll Lock status)

I found another reference, but I still can't make it work:

https://community.st.com/s/question/0D50X00009XkewLSAR/setreport-usb-hid-class-request-for-stm32

I found another reference

"In the following example the function is used to turn on the NUM LOCK, CAPS LOCK and SCROLL LOCK LEDs on a keyboard. The HID report is sent over the control endpoint. The _OnCompletion callback function is called at the end of data transfer."

/*********************************************************************
*
* _TurnOnKeyboardLEDs
*
* Function description
* Turns on NUM LOCK, CAPS LOCK and SCROLL LOCK LEDs on a keyboard.
*
* Parameters
* hInterface Handle to a HID device
*/
static void _TurnOnKeyboardLEDs(USBH_INTERFACE_HANDLE hInterface) {
 USBH_URB Urb;
 U8 LedState;
 LedState = 0x07;
 Urb.Header.pContext = NULL;
 Urb.Header.Function = USBH_FUNCTION_CONTROL_REQUEST;
 Urb.Header.pfOnCompletion = _OnCompletion;
 Urb.Request.ControlRequest.Setup.Type = 0x21;
 Urb.Request.ControlRequest.Setup.Request = 0x09;
 Urb.Request.ControlRequest.Setup.Value = 0x0200;
 Urb.Request.ControlRequest.Setup.Index = 0;
 Urb.Request.ControlRequest.Setup.Length = 1;
 Urb.Request.ControlRequest.pBuffer = &LedState;
 Urb.Request.ControlRequest.Length = 1;
 USBH_SubmitUrb(hInterface, &Urb);
}

http://www.farnell.com/datasheets/1912494.pdf

I found another reference:

"you should be able to send 8 bytes to the keyboard using the "USBHost_Send".

Note that sends data to endpoint, It is non blocking function. After calling it, user should poll transaction status on the endpoint with USBHost_GetTransactionStatus.

Also, on the page.59 you should find how the Report should look:

(Not found) http://www.usb.org/developers/hidpage/HID1_11.pdf"

Source: https://forum.mikroe.com/viewtopic.php?t=68414

(New link) https://www.usb.org/sites/default/files/documents/hid1_11.pdf

I found another reference:

"Hi anyone looking at this thread, the USBH_HID_SetReport can be used to control the LED status of a keyboard from a host device. Unfortunately there must have been some issues with the compatibility between STM Cube and IAR as when I have tried the same code I was trying with IAR on True Studio the function works. I have asked ST if this is a bug."

https://community.st.com/s/question/0D50X0000B0yHZj/i-am-struggling-with-how-and-where-to-implement-the-led-controls-caps-lock-etc-of-a-keyboard-as-far-as-i-understand-it-this-is-accomplished-through-a-usbhhidsetreportphost-0x02-0x00-rep-0x01-please-help

I managed to make it work, but I don't know why it's working this way, I understood that I should send data in another way, based on this document, on page 79 (this information doesn't seem to have much explanation on the Internet):

https://www.usb.org/sites/default/files/documents/hid1_11.pdf

I saw a lot of people suggesting things but it seems that nobody had been able to do with STM32 and USB Host using STM32CubeIDE,

I hope it's revised and incorporated in a sample code, it's unfortunate that a company like ST can read the keys and can't give an example of how to light an LED on the keyboard.

usb_host.c:

// 0B001: NumLock
// 0B010: Caps Lock
// 0B100: Scroll Lock
// 0B111: NumLock, Caps Lock and Scroll Lock
uint8_t LED_status = 7; // 7 = 0B111
uint8_t LED_status_old = 0;
 
USBH_StatusTypeDef USB_Set_Keyboard_LED_Status(void) {
	if (LED_status_old == LED_status) {
		return HAL_OK;
	}
 
	LED_status_old = LED_status;
 
	uint8_t kbd_led[2] = { 0x00, 0x00 };
 
	USBH_StatusTypeDef ret = HAL_BUSY;
	USBH_StatusTypeDef ret2 = HAL_OK;
 
	kbd_led[0] = LED_status & 7;
 
	for(uint8_t timeout = 0; timeout < 100; timeout++) {
		ret = USBH_HID_SetReport(&hUsbHostFS, 0x02U, 0U, kbd_led, sizeof(kbd_led));
 
		// 7x ret=1 ???
		USBH_DbgLog("USBH_HID_SetReport return: %d", ret);
 
		if(ret == ret2){
			break;
		}
	}
 
	/* This part reads the memory that is on the keyboard. */
	for (uint8_t timeout = 0; timeout < 15; timeout++) {
		ret = USBH_HID_GetReport(&hUsbHostFS, 0x02U, 0U, kbd_led,
				sizeof(kbd_led));
 
		UsrLog("USBH_HID_GetReport return: %d; kbd_led: %d", ret, kbd_led[0]);
		HAL_Delay(1);
 
		if (ret == ret2) {
			break;
		}
	}
 
	if (kbd_led[0] == (LED_status & 7)) {
		return HAL_OK;
	} else {
		return HAL_ERROR;
	}
}

usbh_core.c:

uint32_t keyboard_led_status_tick = 0;
 
/**
 * @brief USBH_Process
 * Background process of the USB Core.
 * @param phost: Host Handle
 * @retval USBH Status
 */
USBH_StatusTypeDef USBH_Process(USBH_HandleTypeDef *phost) {
[...]
	case HOST_CLASS:
		/* process class state machine */
		if (phost->pActiveClass != NULL) {
			/* Update keyboard LED status */
			if (HAL_GetTick() > (keyboard_led_status_tick + 10)) {
				keyboard_led_status_tick = HAL_GetTick();
				HID_HandleTypeDef *HID_Handle =
						(HID_HandleTypeDef*) phost->pActiveClass->pData;
				if (HID_Handle->Init == USBH_HID_KeybdInit) {
					USB_Set_Keyboard_LED_Status();
				}
			}
 
			phost->pActiveClass->BgndProcess(phost);
		}
		break;
 
	case HOST_DEV_DISCONNECTED:
[...]

This video is not about USB Host, but it helped me understand a little better about Report Descriptor:

[Custom HID keyboard device | VIDEO 33]:

https://www.youtube.com/watch?v=ZT1tLuo9saw

Best result:

case HOST_CLASS:
		/* process class state machine */
		if (phost->pActiveClass != NULL) {
			/* Update keyboard LED status */
			if (HAL_GetTick() > (keyboard_led_status_tick + 10)) {
				keyboard_led_status_tick = HAL_GetTick();
				HID_HandleTypeDef *HID_Handle =
						(HID_HandleTypeDef*) phost->pActiveClass->pData;
				if (HID_Handle->Init == USBH_HID_KeybdInit) {
					USB_Set_Keyboard_LED_Status();
				}
			}
 
			phost->pActiveClass->BgndProcess(phost);
		}
		break;
 
	case HOST_DEV_DISCONNECTED:

This part reads the memory status that is on the keyboard:

for (uint8_t timeout = 0; timeout < 15; timeout++) {
		ret = USBH_HID_GetReport(&hUsbHostFS, 0x02U, 0U, kbd_led,
				sizeof(kbd_led));
 
		USBH_DbgLog("USBH_HID_GetReport return: %d; kbd_led: %d", ret, kbd_led[0]);
		HAL_Delay(1);
 
		if (ret == ret2) {
			break;
		}
	}

I tried this after seeing someone say it wasn't possible. Again a misinterpretation of the confusing USB protocol manual:

https://community.st.com/s/global-search/%5Busb%20host%5D%20keyboard%20num%20lock

there is no way to read out the state of LEDs from the keyboard (it even may not implement the LEDs at all). This is even explicitly stated in the standard (HID1.11) in Appendix C:

Synchronization between LED states and CAPS LOCK , NUM L OCK , SCROLL L OCK ,

COMPOSE , and KANA events is maintained by the host and NOT the keyboard

I think the best way to control the status of these functions, indicated via the keyboard's LED, is like this:

• Press key (eg NumLock key)
• Update LED status
• If the LED was updated successfully, then the system updates the control variable (eg NumLock_status = ON)

Note: This code is being developed for use in this project (It's still not functional): https://github.com/rtek1000/Datalogger_2039