docs: add an example for streaming feature (#99)

Author: kienvo

BadgeBLE.md

@@ -231,3 +231,9 @@ Returns:
 - Parameters out of range: `0xff`.
 - `speed_ms` or `brightness_level` is out of allowed range: `0x02`.
 - Success: `0x00`.
+
+#### Example
+
+There were some examples created for a better understanding of this next-gen protocol. This requires expect and bluez to be installed.
+
+Put the badge in Bluetooth mode, or enable the always-on BLE. Identify the badge’s MAC address. Put it in the script. Then, in the project root directory, for example, run `./example/streaming.sh` to test the streaming feature.

example/streaming.sh

@@ -0,0 +1,50 @@
+#!/usr/bin/expect -f
+
+set device "5C:53:10:B8:3D:8F"
+set timeout 10
+
+spawn bluetoothctl
+expect "Agent registered"
+
+# 1. Scan
+# This should be run only once externally,
+# as bluetoothctl would remember the last connected device.
+# So comment the 2 lines below would speed up process.
+send -- "scan on\r"
+expect "$device"
+
+# 2. Connect
+send -- "connect $device\r"
+expect "Connection successful"
+
+# 3. Select attribute (characteristic 0xf057)
+send -- "gatt.select-attribute 0000f057-0000-1000-8000-00805f9b34fb\r"
+
+# 4. Enter streaming mode
+# (0x02 = streaming_setting, 0x00 = enter streaming mode)
+send -- "gatt.write '02 00'\r"
+expect "Attempting to write"
+sleep 1
+
+# 5. Write bitmap content to the badge
+# this will draw 2 first lines on the screen
+send -- "gatt.write '03 0xff 0xff 0xff 0xff'\r"
+expect "Attempting to write"
+sleep 5
+
+# Write an entire screen with increment values
+send -- "gatt.write '03 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 \
+22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 \
+48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 \
+74 75 76 77 78 79 80 81 82 83 84 85 86 87 88'\r"
+expect "Attempting to write"
+sleep 5
+
+# 6. Exit streaming mode (if needed)
+# (0x02 = streaming_setting, 0x01 = leave streaming mode)
+send -- "gatt.write '02 01'\r"
+expect "Attempting to write"
+sleep 1
+
+send -- "exit\r"
+expect eof

src/main.c

@@ -295,7 +295,7 @@ uint8_t stream_bitmap(uint8_t *params, uint16_t len)
 		return -1;
 	}
 
-	tmos_memcpy(fb, params, min(LED_COLS, len));
+	tmos_memcpy(fb, params, min(LED_COLS * 2, len));
 	return 0;
 }