MSP30FR2433: SLEEP command not working correctly

[kreitzz 0]

Hello!

I am currently moving a project from MSP430G2553 MCU to newer MSPFR2433. I have MSP-EXP430FR2433 board and Energia-1.6.10E18 IDE Software.

From the beginning I saw very strange thing - big difference in DELAY  and SLEEP intervals, but only on MSP-EXP430FR2433 board. 

For example, even simplest elementary code for BLINK run on MSP-EXP430FR2433:

#define LED RED_LED

void setup() { 
pinMode(LED, OUTPUT); 
}
void loop() {
digitalWrite(LED, HIGH); // turn the LED on (HIGH is the voltage level)
sleep(4000); // wait for 4 seconds
digitalWrite(LED, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}

On this board  interval for ON (sleep command) visually is almost equal to OFF (delay command) interval (!).  So SLEEP command is running about 4 times faster, than DELAY. 

While same code on MSP-EXP430G2 with MSP430G2553 and MSP-EXP430FR5969 boards is working fine.

What is the reason ? It looks, like Energia library for MSP430FR2433 has some issues...Is it possible to fix it ?

I understand, that MSP430G2xxx and MSP430FR2xxx have differences, but some basic functions should be running the same...isn't it ?

[LIJsselstein 9]

I think this is because, when there is no external XTAL connected, Energia (wiring) usually falls back to the VLO source (~12k Hz). But on the FR2433 the clock falls back to the REFO source which runs about 3x faster ( ~32768 Hz).

However the code in wiring.h does not reflect this. Please look around line 144 in wiring.c (hardware/energia/msp430/cores/msp430/wiring.c):

/* ACLK = VLO = ~ 12 KHz */
vlo_freq = 8000;
/* Source ACLK from REFO */
CSCTL4 |= SELA__REFOCLK;

Where I think it should be:

/* ACLK = REFO = ~ 32 KHz */
vlo_freq = 32768;
/* Source ACLK from REFO */
CSCTL4 |= SELA__REFOCLK;

Since Sleep() uses the clock for timing and Delay() uses the CPU frequency for timing, this could explain your difference.

Pinging @StefanSch

[Jamesgrr 1]

. Hey Kreitzz, 

I would be interested to know if you have tried using sleepseconds with any different results. I am using the same board and am hoping to get low power sleep working as well.