From 45c8997e49650fc86c4323304d67ca87c7ad1e64 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <daniel.friesel@uos.de>
Date: Mon, 30 Nov 2020 15:56:14 +0100
Subject: msp430fr5994: add experimental support for 32kHz operation via LFXT

---
 src/arch/msp430fr5994lp/arch.cc          | 14 +++++++++++++-
 src/arch/msp430fr5994lp/driver/stdout.cc |  6 ++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

(limited to 'src/arch/msp430fr5994lp')

diff --git a/src/arch/msp430fr5994lp/arch.cc b/src/arch/msp430fr5994lp/arch.cc
index 9b243d1..024b246 100644
--- a/src/arch/msp430fr5994lp/arch.cc
+++ b/src/arch/msp430fr5994lp/arch.cc
@@ -37,6 +37,8 @@ void Arch::setup(void)
 	// 8MHz DCO
 	CSCTL0_H = CSKEY >> 8;
 	CSCTL1 = DCOFSEL_0;
+#elif F_CPU == 32768UL
+	CSCTL0_H = CSKEY >> 8;
 #else
 #error Unsupported F_CPU
 #endif
@@ -50,7 +52,7 @@ void Arch::setup(void)
 	CSCTL0_H = 0;
 
 
-#ifdef WITH_LOOP
+#if defined(WITH_LOOP) || F_CPU == 72368UL
 	// enable LXFT for RTC
 	CSCTL0_H = CSKEY >> 8;
 	CSCTL4 &= ~LFXTOFF;
@@ -82,6 +84,12 @@ void Arch::setup(void)
 	TA0CTL |= TACLR;
 #endif /* TIMER_US */
 
+#if F_CPU == 32768UL
+	CSCTL0_H = CSKEY >> 8;
+	CSCTL2 = SELA__LFXTCLK | SELS__LFXTCLK | SELM__LFXTCLK;
+	CSCTL0_H = 0;
+#endif
+
 #if defined(WITH_LOOP) || defined(TIMER_S)
 	// 1s per wakeup for loop. Independent of SMCLK/F_CPU
 	TA1CTL = TASSEL__ACLK | ID__8 | MC__UP;
@@ -153,6 +161,10 @@ void Arch::sleep_ms(unsigned int const ms)
 	TA3CTL = TASSEL__SMCLK | ID__8; // /8
 	TA3EX0 = 0; // /1 -> /8 (125 kHz)
 	TA3CCR0 = ms * 125;
+#elif F_CPU == 32768UL
+	TA3CTL = TASSEL__SMCLK | ID__8; // /8
+	TA3EX0 = 0; // /1 -> /8 (4.096 kHz)
+	TA3CCR0 = ms * 4;
 #else
 #error Unsupported F_CPU
 #endif /* F_CPU */
diff --git a/src/arch/msp430fr5994lp/driver/stdout.cc b/src/arch/msp430fr5994lp/driver/stdout.cc
index b3e8b4d..f3c219a 100644
--- a/src/arch/msp430fr5994lp/driver/stdout.cc
+++ b/src/arch/msp430fr5994lp/driver/stdout.cc
@@ -32,6 +32,12 @@ void StandardOutput::setup()
 	UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
 	UCA0MCTLW = 0x5500;
 	UCA0BR0 = 8;
+#elif F_CPU == 32768UL
+	// Limited to 9600 Baud
+	// 32768 / 9600 == 3.413333 -> UCOS16 = 0, UCBR0 = 3, UCBRF0 = 0, UCBRS0 = 0x92 ("0.4003")
+	UCA0CTLW0 = UCSWRST | UCSSEL__SMCLK;
+	UCA0MCTLW = 0x9200;
+	UCA0BR0 = 3;
 #else
 #error Unsupported F_CPU
 #endif
-- 
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