vector and iterator problem

[BeBu]

Hi i got following code:

void STM32SPI::handleInterrupt() {
	if (SPI_I2S_GetITStatus(spiport, SPI_I2S_IT_TXE) == SET) {
		if (sendBufferPos != sendBuffer.end()) {
			SPI_I2S_SendData(spiport, *sendBufferPos);
			sendBufferPos++;
		} else {
			enableInterrupt(false);
			sendBuffer.clear();
		}
	}
	if (SPI_I2S_GetITStatus(spiport, SPI_I2S_IT_RXNE) == SET) {
		receiveBuffer.push_back((u8) SPI_I2S_ReceiveData(spiport));
	}
}

void STM32SPI::send() {
	sendBufferPos == sendBuffer.begin();
	enableInterrupt();
}

with sendBuffer and sendBufferPos beeing class members:

class STM32SPI{
	vector<u8>::iterator sendBufferPos;
	vector<u8> sendBuffer;
}

i am trying to do this:
after calling send the iterator is set to the begin of the vector and the interrupt is enabled, now everytime the interrupt handler is called, the iterator *should* move to
the next position till end(). but it doesnt. sendBufferPos != sendBuffer.end() is never true.
I am not touching the vector, so the iterator should not be invalidated as far as i know.

P.S.

the code is running on a microprocessor