From 61ff5bbb4cae80997562bcd4edd5c35a4f801b44 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Thu, 25 Oct 2018 15:01:23 +0200
Subject: softi2c: Work around MSP430 timing issues with softi2c_timer=1

---
 src/driver/soft_i2c.cc | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'src')

diff --git a/src/driver/soft_i2c.cc b/src/driver/soft_i2c.cc
index e16c4a1..de634b1 100644
--- a/src/driver/soft_i2c.cc
+++ b/src/driver/soft_i2c.cc
@@ -176,6 +176,15 @@ signed char SoftI2C::xmit(unsigned char address,
 
 volatile unsigned char timer_done = 0;
 
+/*
+ * Note: On MSP430, if F_CPU / F_I2C < 60 (approx.), await_timer() does not
+ * work.  Probably related to missed interrupts / not enough cycles between
+ * start and idle?  We work around this for now by simulating an immediate
+ * return in these cases.
+ */
+#if MULTIPASS_ARCH_msp430fr5969lp && ((F_CPU / F_I2C) < 60)
+inline void await_timer() {}
+#else
 inline void await_timer()
 {
 	timer_done = 0;
@@ -185,6 +194,7 @@ inline void await_timer()
 	}
 	timer.stop();
 }
+#endif
 
 signed char SoftI2C::setup()
 {
-- 
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