Merge pull request #4864 from sandeepmistry/avr-usb-tx

Subtract one from USB_EP_SIZE in USB_SendSpace

Merge pull request #4864 from sandeepmistry/avr-usb-tx
Subtract one from USB_EP_SIZE in USB_SendSpace
2717fbe0 · Arturo Guadalupi · GitHub · 2a10caa4 · 5e3d08af · 2717fbe0
Commit 2717fbe0 authored Jul 11, 2016 by Arturo Guadalupi Committed by GitHub Jul 11, 2016
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cores/arduino/USBCore.cpp cores/arduino/USBCore.cpp +3 -1

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--- a/cores/arduino/USBCore.cpp
+++ b/cores/arduino/USBCore.cpp
@@ -255,7 +255,9 @@ u8 USB_SendSpace(u8 ep)
 	LockEP lock(ep);
 	if (!ReadWriteAllowed())
 		return 0;
-	return USB_EP_SIZE - FifoByteCount();
+	// subtract 1 from the EP size to never send a full packet,
+	// this avoids dealing with ZLP's in USB_Send
+	return USB_EP_SIZE - 1 - FifoByteCount();
 }

 //	Blocking Send of data to an endpoint