From e8e8f93bcf0cdc8d72d35662db5a1da4716762b8 Mon Sep 17 00:00:00 2001
From: tmk <nobody@nowhere>
Date: Tue, 8 Oct 2013 12:23:25 +0900
Subject: [PATCH] Fix ADB missing keystrokes problem Thanks, blargg! #14

- Add delay between scans to prevent overlaod of ADB keyboard controllers
- <http://geekhack.org/index.php?topic=14290.msg1068919#msg1068919>
---
 converter/adb_usb/matrix.c | 1 +
 protocol/adb.c             | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/converter/adb_usb/matrix.c b/converter/adb_usb/matrix.c
index ee17f655..566592c9 100644
--- a/converter/adb_usb/matrix.c
+++ b/converter/adb_usb/matrix.c
@@ -85,6 +85,7 @@ uint8_t matrix_scan(void)
     uint8_t key0, key1;
 
     is_modified = false;
+    _delay_ms(16);  // delay for preventing overload of poor ADB keyboard controller
     codes = adb_host_kbd_recv();
     key0 = codes>>8;
     key1 = codes&0xFF;
diff --git a/protocol/adb.c b/protocol/adb.c
index e4e26b7d..155d223f 100644
--- a/protocol/adb.c
+++ b/protocol/adb.c
@@ -83,6 +83,12 @@ bool adb_host_psw(void)
 }
 #endif
 
+/*
+ * Don't call this in a row without the delay, otherwise it makes some of poor controllers
+ * overloaded and misses strokes. Recommended delay is 16ms.
+ *
+ * Thanks a lot, blargg! <http://geekhack.org/index.php?topic=14290.msg1068919#msg1068919>
+ */
 uint16_t adb_host_kbd_recv(void)
 {
     uint16_t data = 0;