From 0883a7e72f7122b307798205441c96120446bf75 Mon Sep 17 00:00:00 2001
From: Pavol Rusnak <stick@gk2.sk>
Date: Tue, 17 Jan 2017 20:17:15 +0100
Subject: [PATCH] stmhal: Implement SNAK/CNAK mechanism for USB HID receive.
This implements flow control in case user does not call recv method often
enough (it tells host side to stop sending more data).
---
stmhal/usbd_hid_interface.c | 6 +++++-
stmhal/usbdev/class/inc/usbd_cdc_msc_hid.h | 2 ++
stmhal/usbdev/class/src/usbd_cdc_msc_hid.c | 18 ++++++++++++++++++
3 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/stmhal/usbd_hid_interface.c b/stmhal/usbd_hid_interface.c
index 4987314bd..7a420c330 100644
--- a/stmhal/usbd_hid_interface.c
+++ b/stmhal/usbd_hid_interface.c
@@ -89,7 +89,8 @@ static int8_t HID_Itf_Receive(uint8_t* Buf, uint32_t Len) {
// initiate next USB packet transfer, to append to existing data in buffer
USBD_HID_SetRxBuffer(&hUSBDDevice, buffer[current_write_buffer]);
USBD_HID_ReceivePacket(&hUSBDDevice);
-
+ // Set NAK to indicate we need to process read buffer
+ USBD_HID_SetNAK(&hUSBDDevice);
return USBD_OK;
}
@@ -125,6 +126,9 @@ int USBD_HID_Rx(uint8_t *buf, uint32_t len, uint32_t timeout) {
memcpy(buf, buffer[current_read_buffer], last_read_len);
current_read_buffer = !current_read_buffer;
+ // Clear NAK to indicate we are ready to read more data
+ USBD_HID_ClearNAK(&hUSBDDevice);
+
// Success, return number of bytes read
return last_read_len;
}
diff --git a/stmhal/usbdev/class/inc/usbd_cdc_msc_hid.h b/stmhal/usbdev/class/inc/usbd_cdc_msc_hid.h
index 7cb64fd84..5f0502766 100644
--- a/stmhal/usbdev/class/inc/usbd_cdc_msc_hid.h
+++ b/stmhal/usbdev/class/inc/usbd_cdc_msc_hid.h
@@ -116,5 +116,7 @@ uint8_t USBD_HID_SetRxBuffer(USBD_HandleTypeDef *pdev, uint8_t *pbuff);
uint8_t USBD_HID_ReceivePacket(USBD_HandleTypeDef *pdev);
int USBD_HID_CanSendReport(USBD_HandleTypeDef *pdev);
uint8_t USBD_HID_SendReport(USBD_HandleTypeDef *pdev, uint8_t *report, uint16_t len);
+uint8_t USBD_HID_SetNAK(USBD_HandleTypeDef *pdev);
+uint8_t USBD_HID_ClearNAK(USBD_HandleTypeDef *pdev);
#endif // _USB_CDC_MSC_CORE_H_
diff --git a/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c b/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
index 3ebc7d828..cfae7224d 100644
--- a/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
+++ b/stmhal/usbdev/class/src/usbd_cdc_msc_hid.c
@@ -1093,6 +1093,24 @@ uint8_t USBD_HID_SendReport(USBD_HandleTypeDef *pdev, uint8_t *report, uint16_t
return USBD_OK;
}
+uint8_t USBD_HID_SetNAK(USBD_HandleTypeDef *pdev) {
+ // get USBx object from pdev (needed for USBx_OUTEP macro below)
+ PCD_HandleTypeDef *hpcd = pdev->pData;
+ USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
+ // set NAK on HID OUT endpoint
+ USBx_OUTEP(HID_OUT_EP_WITH_CDC)->DOEPCTL |= USB_OTG_DOEPCTL_SNAK;
+ return USBD_OK;
+}
+
+uint8_t USBD_HID_ClearNAK(USBD_HandleTypeDef *pdev) {
+ // get USBx object from pdev (needed for USBx_OUTEP macro below)
+ PCD_HandleTypeDef *hpcd = pdev->pData;
+ USB_OTG_GlobalTypeDef *USBx = hpcd->Instance;
+ // clear NAK on HID OUT endpoint
+ USBx_OUTEP(HID_OUT_EP_WITH_CDC)->DOEPCTL |= USB_OTG_DOEPCTL_CNAK;
+ return USBD_OK;
+}
+
// CDC/MSC/HID interface class callback structure
USBD_ClassTypeDef USBD_CDC_MSC_HID = {
USBD_CDC_MSC_HID_Init,
--
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