alternate button text automatically without click

I would like alternate between 2 pieces of text on a button in 2 sec intervals. This is NOT a click event. I just want the button to rotate between 'click here' and 'download'. This is what Im trying with no luck:

<div class="assetClass customButton1_1Div" id="download_btn1">
<input type="button" class="customButton1_1" name="button1_1" value="click here" title="download_btn1" />
</div>

setInterval(toggle, 2000);
function toggle() {
document.getElementByName("button1_1").value = "download";
}