boards/olimex-msp430-h1611: uart_stdio @ 9600 Bd

boards/olimex-msp430-h1611/Makefile.include

@@ -3,10 +3,16 @@ PORT_LINUX ?= /dev/ttyUSB0
 PORT_DARWIN ?= $(firstword $(sort $(wildcard /dev/tty.usbserial-MXV*)))
 
 # flash tool configuration
-PROGRAMMER ?= mspdebug
-MSPDEBUG_PROGRAMMER ?= olimex
+PROGRAMMER              ?= mspdebug
+MSPDEBUG_PROGRAMMER     ?= olimex
 
-PROGRAMMERS_SUPPORTED += mspdebug
+PROGRAMMERS_SUPPORTED   += mspdebug
+# UART @ 115200 Bd is not reliable with a CPU clock of ~ 5 MHz, occasionally
+# chars get lost. Adding an 8 MHz crystal or an external resistor so that the
+# DCO can reach 8 MHz does yield the speed bump needed for a more reliable
+# UART connection @ 115200 Bd
+
+BAUD                    ?= 9600
 
 # When freshly plugged in the Olimex MSP430-JTAG-Tiny debugger provides a
 # ttyACM interface, which is only available until the first flashing. A
@@ -24,3 +30,5 @@ TTY_SELECT_CMD := $(RIOTTOOLS)/usb-serial/ttys.py \
                   $(RIOTTOOLS)/usb-serial/ttys.py \
                   --most-recent \
                   --format path serial
+
+CFLAGS += -DSTDIO_UART_BAUDRATE=$(BAUD)

boards/olimex-msp430-h1611/include/periph_conf.h

@@ -34,6 +34,10 @@ extern "C" {
  * @brief   Clock configuration
  */
 static const msp430_clock_params_t clock_params = {
+    /* Without an external resistor, the DCO frequency typically tops out
+     * at something like 5 MHz. However, the DCO calibration just picks the
+     * closet possible value, in this case it will go for the highest frequency
+     * the silicon at hand can run at. */
     .target_dco_frequency = MHZ(8),
     .lfxt1_frequency = 32768,
     .main_clock_source = MAIN_CLOCK_SOURCE_DCOCLK,