From 30c4f72770568749b4230a6b598e3fb87a065e91 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Mon, 27 Aug 2018 13:11:20 +0200
Subject: msp430: Add preprocessor macro for CPU speed

---
 src/arch/msp430fr5969lp/driver/spi_b.cc | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'src/arch/msp430fr5969lp/driver')

diff --git a/src/arch/msp430fr5969lp/driver/spi_b.cc b/src/arch/msp430fr5969lp/driver/spi_b.cc
index 2eb3a79..0fa71da 100644
--- a/src/arch/msp430fr5969lp/driver/spi_b.cc
+++ b/src/arch/msp430fr5969lp/driver/spi_b.cc
@@ -1,6 +1,10 @@
 #include "driver/spi_b.h"
 #include <msp430.h>
 
+#ifndef F_I2C
+#define F_I2C 1000000UL
+#endif
+
 void SPI::setup()
 {
 	UCB0CTLW0 |= UCSWRST;
@@ -22,7 +26,8 @@ void SPI::setup()
 	//P1REN |= BIT6;
 
 	UCB0CTLW0 = UCCKPH | UCMSB | UCMST | UCSYNC | UCMODE_0 | UCSSEL__SMCLK | UCSWRST;
-	UCB0BRW = 15; // /16 -> 1MHz
+	UCB0BRW = (F_CPU/F_I2C)-1; // /16 -> 1MHz
+	// UCB0BRW = (F_CPU / F_I2C) - 1
 	UCB0CTLW0 &= ~UCSWRST;
 }
 
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