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authorDaniel Friesel <derf@finalrewind.org>2018-10-15 12:34:39 +0200
committerDaniel Friesel <derf@finalrewind.org>2018-10-15 12:34:39 +0200
commitea0c6d43bc3987b7e58d5b61b957bc7a58bc3bc7 (patch)
treeb0bb91f09fa1a62690972ee7b9bf9b6b4325d103 /src/arch/msp430fr5969lp
parent60d9448acc7331a599cbdb4b1007ec45419f57fb (diff)
MSP430 stdout: Support more CPU frequencies
Diffstat (limited to 'src/arch/msp430fr5969lp')
-rw-r--r--src/arch/msp430fr5969lp/driver/stdout.cc30
1 files changed, 29 insertions, 1 deletions
diff --git a/src/arch/msp430fr5969lp/driver/stdout.cc b/src/arch/msp430fr5969lp/driver/stdout.cc
index 321785b..b3e8b4d 100644
--- a/src/arch/msp430fr5969lp/driver/stdout.cc
+++ b/src/arch/msp430fr5969lp/driver/stdout.cc
@@ -1,12 +1,40 @@
#include "driver/stdout.h"
#include <msp430.h>
+/*
+ * Baud rate calculation according to datasheet:
+ * N := f_{BRCLK} / Baudrate = F_CPU / 115200 in our case
+ * if N <= 16: OS16 = 0, UCBR0 = int(N)
+ * if N > 16: OS16 = 1, UCBR0 = int(N/16), UCBRF0 = int(((n/16) - int(n/16)) * 16) = int(N)%16
+ * Set UCBRS0 according to table 21-4
+ */
+
void StandardOutput::setup()
{
UCA0CTLW0 |= UCSWRST;
+#if F_CPU == 16000000UL
+ // 16M / 115200 == 138.88889 -> UCOS16 = 1, UCBR0 = 16, UCBRF0 = 10, UCBRS0 = 0xf7 ("0.8751")
+ UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
+ UCA0MCTLW = UCOS16 | (10<<4) | 0xF700;
+ UCA0BR0 = 8;
+#elif F_CPU == 8000000UL
+ // 8M / 115200 == 69.444444 -> UCOS16 = 1, UCBR0 = 4, UCBRF0 = 5, UCBRS0 = 0x55 ("0.4378")
+ UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
+ UCA0MCTLW = UCOS16 | (5<<4) | 0x5500;
+ UCA0BR0 = 4;
+#elif F_CPU == 4000000UL
+ // 4M / 115200 == 34.722222 -> UCOS16 = 1, UCBR0 = 2, UCBRF0 = 2, UCBRS0 = 0xbb ("0.7147")
+ UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
+ UCA0MCTLW = UCOS16 | (2<<4) | 0xbb00;
+ UCA0BR0 = 2;
+#elif F_CPU == 1000000UL
+ // 1M / 115200 == 8.6805556 -> UCOS16 = 0, UCBR0 = 8, UCBRF0 = 0, UCBRS0 = 0xd6 ("0.6667")
UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
- UCA0MCTLW = UCOS16 | (10<<5) | 0xF700;
+ UCA0MCTLW = 0x5500;
UCA0BR0 = 8;
+#else
+#error Unsupported F_CPU
+#endif
UCA0IRCTL = 0;
UCA0ABCTL = 0;