Frame rate benchmarking tool

README.md

@@ -162,6 +162,14 @@ Byte Offset | Bits   | Description
 1           | 0      | Disable dithering
 2 … 63      | 7 … 0  | (reserved)
 
+In addition to the OUT endpoint, the device also supports vendor-specific control requests:
+
+bmRequestType | bRequest | wValue | wIndex | wLength | Description
+------------- | -------- | ------ | ------ | ------- | ---------------------------------------------
+0xC0          | 0x01     | 0      | 0      | 4       | Read frame counter (32-bit, little endian)
+0xC0          | 0x7E     | x      | 4      | x       | Read Microsoft WCID descriptor
+0xC0          | 0x7E     | x      | 5      | x       | Read Microsoft Extended Properties descriptor
+
 Contact
 -------
 

firmware/fadecandy.cpp

@@ -499,6 +499,9 @@ extern "C" int main()
             for (unsigned i = 0; i < CHANNELS_TOTAL; ++i)
                 residual[i] = 0;
         }
+
+        // Performance counter, for monitoring frame rate externally
+        perf_frameCounter++;
     }
 
     // Reboot into DFU bootloader

firmware/usb_dev.c

@@ -55,6 +55,9 @@ uint16_t usb_rx_byte_count_data[NUM_ENDPOINTS];
 
 static uint8_t reply_buffer[8];
 
+// Performance counters
+volatile uint32_t perf_frameCounter;
+
 static uint8_t tx_state[NUM_ENDPOINTS];
 #define TX_STATE_BOTH_FREE_EVEN_FIRST   0
 #define TX_STATE_BOTH_FREE_ODD_FIRST    1
@@ -302,6 +305,12 @@ static void usb_setup(void)
         endpoint0_stall();
         return;
 
+      case 0x01C0:      // Read frame counter
+      case 0x01C1:
+        data = (uint8_t*) &perf_frameCounter;
+        datalen = sizeof perf_frameCounter;
+        break;
+
       case (MSFT_VENDOR_CODE << 8) | 0xC0:      // Get Microsoft descriptor
       case (MSFT_VENDOR_CODE << 8) | 0xC1:
         if (setup.wIndex == 0x0004) {

firmware/usb_dev.h

@@ -59,6 +59,9 @@ extern volatile uint8_t usb_dfu_state;
 #define DFU_appIDLE    0
 #define DFU_appDETACH  1
 
+// Performance counters
+extern volatile uint32_t perf_frameCounter;
+
 extern uint16_t usb_rx_byte_count_data[NUM_ENDPOINTS];
 static inline uint32_t usb_rx_byte_count(uint32_t endpoint) __attribute__((always_inline));
 static inline uint32_t usb_rx_byte_count(uint32_t endpoint)

tools/benchmark.py

+#!/usr/bin/env python
+#
+# Read the device's performance counters, calculate benchmark values.
+#
+# Micah Elizabeth Scott
+# This example code is released into the public domain.
+#
+
+import usb.core
+import usb.util
+import time, struct, sys
+
+dev = usb.core.find(idVendor=0x1d50, idProduct=0x607a)
+if not dev:
+    raise IOError("No Fadecandy interfaces found")
+
+dev.set_configuration()
+
+print "Serial number: %s" % usb.util.get_string(dev, 255, dev.iSerialNumber)
+
+def readFrameCounter():
+    return struct.unpack('<I', dev.ctrl_transfer(0xC0, 0x01, 0, 0, 4, 1000))[0]
+
+sys.stderr.write("Calculating frame rate average...\n")
+t1 = time.time()
+c1 = readFrameCounter()
+
+try:
+    while True:
+        time.sleep(0.1)
+        t2 = time.time()
+        c2 = readFrameCounter()
+        fps = ((c2 - c1) & 0xFFFFFFFF) / (t2 - t1)
+        sys.stderr.write("\r   %.3f FPS   " % fps)
+except KeyboardInterrupt:
+    sys.stderr.write("\n")
+