add sweep

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@5477 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/zoom.c

@@ -50,9 +50,14 @@ int main(void)
 					dac_write(0xFFFF);
 				}
 				break;				
+			case 's':
+				for (v = 0; v < 65536; v++) {
+					dac_write(v);
+				}
+				break;				
 			default:
 				uart1_put_string("ADC: Read Convert\r\n");
-				uart1_put_string("DAC: 123456789 Toggle\r\n");
+				uart1_put_string("DAC: 123456789 Toggle Sweep\r\n");
 				break;
 		}
 	}