Cytron Technical Forum

I just want to know the sensitivity of this sensor.high or low?what about their response?

Which humidity sensor? Don you have the part number or model name? And don the sensor come with datasheet or document?

Hey, have u read the user manual? Should have mentioned there.

Hi, assuming you are asking about humidity sensor on Cytron site: SN-HMD.

The User's Manual, there is a graph on page 5 showing the relationship between the voltage and humidity, in %RH and another table showing the similar data.

yes..manual stated all the detail...base on my experiences...SN-HMD... gave a very good response.....have fun

royalstorm7@yahoo.com

royalstorm7 WROTE:yes..manual stated all the detail...base on my experiences...SN-HMD... gave a very good response.....have fun

SN-HMD temperature reading give some delay response, LM35 give more faster response for temperature.

Hi,

Anyone here know how to convert the analog output of the HSM-20G humidity sensor to the actual humidity value in %RH?
Can someone show me the calculation here?
Thanks.

Bridget Tham WROTE:Hi,

Anyone here know how to convert the analog output of the HSM-20G humidity sensor to the actual humidity value in %RH?
Can someone show me the calculation here?
Thanks.

In the datasheet, was given graph output voltage vs humidity.
You can do 2 ways.
1. Every 2 point assume as straight line and do linear equation for every 2 points. Ex like distance sensor.
2. From the tabulated data, you can find best fit equation. I'm using software Maple and it's called Curve Fitting. Ex like current sensor, ACS712.

Hi,

Thanks for the reply. I tried and put in the linear equation given by the graph, but I still can't get the accurate value.
The following is the modified sample code for IAR Embedded Workbench MSP430 and I'm using the eZ430-RF2500 boards from Texas Instrument. FYI, the ADC pin that I'm using is Channel A0 which is pin 3 on the target board. While the humidity sensor that I'm using is HSM-20G. The modified code is in red color which is to sense for the humidity parameter. Can someone help me? Since I'm not familiar to this. Thanks.

#include "bsp.h"
#include "mrfi.h"
#include "nwk_types.h"
#include "nwk_api.h"
#include "bsp_leds.h"
#include "bsp_buttons.h"
#include "vlo_rand.h"

/*------------------------------------------------------------------------------
* Defines
*----------------------------------------------------------------------------*/
/* How many times to try a TX and miss an acknowledge before doing a scan */
#define MISSES_IN_A_ROW 2

/*------------------------------------------------------------------------------
* Prototypes
*----------------------------------------------------------------------------*/
static void linkTo(void);
void createRandomAddress(void);
__interrupt void ADC10_ISR(void);
__interrupt void Timer_A (void);

/*------------------------------------------------------------------------------
* Globals
------------------------------------------------------------------------------*/
static linkID_t sLinkID1 = 0;
/* Temperature offset set at production */
volatile int * tempOffset = (int *)0x10F4;
/* Initialize radio address location */
char * Flash_Addr = (char *)0x10F0;
/* Work loop semaphores */
static volatile uint8_t sSelfMeasureSem = 0;

/*------------------------------------------------------------------------------
* Main
*----------------------------------------------------------------------------*/
void main (void)
{
addr_t lAddr;

/* Initialize board-specific hardware */
BSP_Init();

/* Check flash for previously stored address */
if(Flash_Addr[0] == 0xFF && Flash_Addr[1] == 0xFF &&
Flash_Addr[2] == 0xFF && Flash_Addr[3] == 0xFF )
{
createRandomAddress(); // Create and store a new random address
}

/* Read out address from flash */
lAddr.addr[0] = Flash_Addr[0];
lAddr.addr[1] = Flash_Addr[1];
lAddr.addr[2] = Flash_Addr[2];
lAddr.addr[3] = Flash_Addr[3];

/* Tell network stack the device address */
SMPL_Ioctl(IOCTL_OBJ_ADDR, IOCTL_ACT_SET, &lAddr);

/* Initialize TimerA and oscillator */
BCSCTL3 |= LFXT1S_2; // LFXT1 = VLO
TACCTL0 = CCIE; // TACCR0 interrupt enabled
TACCR0 = 12000; // ~ 1 sec
TACTL = TASSEL_1 + MC_1; // ACLK, upmode

/* Keep trying to join (a side effect of successful initialization) until
* successful. Toggle LEDS to indicate that joining has not occurred.
*/
while (SMPL_SUCCESS != SMPL_Init(0))
{
BSP_TOGGLE_LED1();
BSP_TOGGLE_LED2();
/* Go to sleep (LPM3 with interrupts enabled)
* Timer A0 interrupt will wake CPU up every second to retry initializing
*/
__bis_SR_register(LPM3_bits+GIE); // LPM3 with interrupts enabled
}

/* LEDs on solid to indicate successful join. */
BSP_TURN_ON_LED1();
BSP_TURN_ON_LED2();

/* Unconditional link to AP which is listening due to successful join. */
linkTo();

while(1);
}

static void linkTo()
{
uint8_t msg[4];
#ifdef APP_AUTO_ACK
uint8_t misses, done;
#endif

/* Keep trying to link... */
while (SMPL_SUCCESS != SMPL_Link(&sLinkID1))
{
BSP_TOGGLE_LED1();
BSP_TOGGLE_LED2();
/* Go to sleep (LPM3 with interrupts enabled)
* Timer A0 interrupt will wake CPU up every second to retry linking
*/
__bis_SR_register(LPM3_bits+GIE);
}

/* Turn off LEDs. */
BSP_TURN_OFF_LED1();
BSP_TURN_OFF_LED2();

/* Put the radio to sleep */
SMPL_Ioctl(IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_SLEEP, 0);

while (1)
{
/* Go to sleep, waiting for interrupt every second to acquire data */
__bis_SR_register(LPM3_bits);

/* Time to measure */
if (sSelfMeasureSem) {
volatile long temp,a;
int degC, volt;
int humidity;
int results[3];

#ifdef APP_AUTO_ACK
uint8_t noAck;
smplStatus_t rc;
#endif

/* Get temperature */
ADC10CTL1 = INCH_10 + ADC10DIV_4; // Temp Sensor ADC10CLK/5
ADC10CTL0 = SREF_1 + ADC10SHT_3 + REFON + ADC10ON + ADC10IE + ADC10SR;
/* Allow ref voltage to settle for at least 30us (30us * 8MHz = 240 cycles)
* See SLAS504D for settling time spec
*/
__delay_cycles(240);
ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
__bis_SR_register(CPUOFF + GIE); // LPM0 with interrupts enabled
results[0] = ADC10MEM; // Retrieve result
ADC10CTL0 &= ~ENC;

/* Get voltage */
ADC10CTL1 = INCH_11; // AVcc/2
ADC10CTL0 = SREF_1 + ADC10SHT_2 + REFON + ADC10ON + ADC10IE + REF2_5V;
__delay_cycles(240);
ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
__bis_SR_register(CPUOFF + GIE); // LPM0 with interrupts enabled
results[1] = ADC10MEM; // Retrieve result

/* Stop and turn off ADC */
ADC10CTL0 &= ~ENC;
ADC10CTL0 &= ~(REFON + ADC10ON);

/* Get humidity */
ADC10CTL1 = INCH_0 + ADC10DIV_4; // Humidity Sensor ADC10CLK/5
ADC10CTL0 = SREF_1 + ADC10SHT_3 + REFON + ADC10ON + ADC10IE + ADC10SR;
__delay_cycles(240);
ADC10CTL0 |= ENC + ADC10SC; // Sampling and conversion start
__bis_SR_register(CPUOFF + GIE); // LPM0 with interrupts enabled
results[2] = ADC10MEM; // Retrieve result
ADC10CTL0 &= ~ENC;

/* oC = ((A10/1024)*1500mV)-986mV)*1/3.55mV = A10*423/1024 - 278
* the temperature is transmitted as an integer where 32.1 = 321
* hence 4230 instead of 423
*/
temp = results[0];
degC = ((temp - 673) * 4230) / 1024;
if( (*tempOffset) != 0xFFFF )
{
degC += (*tempOffset);
}

/* message format, UB = upper Byte, LB = lower Byte
-------------------------------
|degC LB | degC UB | volt LB |
-------------------------------
0 1 2
*/
temp = results[1];
volt = (temp*25)/512;
a = results[2];
humidity = (a-0.379)/0.032;
msg[0] = degC&0xFF;
msg[1] = (degC>>8)&0xFF;
msg[2] = volt;
msg[3] = humidity;


/* Get radio ready...awakens in idle state */
SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_AWAKE, 0);

#ifdef APP_AUTO_ACK
/* Request that the AP sends an ACK back to confirm data transmission
* Note: Enabling this section more than DOUBLES the current consumption
* due to the amount of time IN RX waiting for the AP to respond
*/
done = 0;
while (!done)
{
noAck = 0;

/* Try sending message MISSES_IN_A_ROW times looking for ack */
for (misses=0; misses < MISSES_IN_A_ROW; ++misses)
{
if (SMPL_SUCCESS == (rc=SMPL_SendOpt(sLinkID1, msg, sizeof(msg), SMPL_TXOPTION_ACKREQ)))
{
/* Message acked. We're done. Toggle LED 1 to indicate ack received. */
BSP_TURN_ON_LED1();
__delay_cycles(2000);
BSP_TURN_OFF_LED1();
break;
}
if (SMPL_NO_ACK == rc)
{
/* Count ack failures. Could also fail becuase of CCA and
* we don't want to scan in this case.
*/
noAck++;
}
}
if (MISSES_IN_A_ROW == noAck)
{
/* Message not acked */
BSP_TURN_ON_LED2();
__delay_cycles(2000);
BSP_TURN_OFF_LED2();
#ifdef FREQUENCY_AGILITY
/* Assume we're on the wrong channel so look for channel by
* using the Ping to initiate a scan when it gets no reply. With
* a successful ping try sending the message again. Otherwise,
* for any error we get we will wait until the next button
* press to try again.
*/
if (SMPL_SUCCESS != SMPL_Ping(sLinkID1))
{
done = 1;
}
#else
done = 1;
#endif /* FREQUENCY_AGILITY */
}
else
{
/* Got the ack or we don't care. We're done. */
done = 1;
}
}
#else

/* No AP acknowledgement, just send a single message to the AP */
SMPL_SendOpt(sLinkID1, msg, sizeof(msg), SMPL_TXOPTION_NONE);

#endif /* APP_AUTO_ACK */

/* Put radio back to sleep */
SMPL_Ioctl( IOCTL_OBJ_RADIO, IOCTL_ACT_RADIO_SLEEP, 0);

/* Done with measurement, disable measure flag */
sSelfMeasureSem = 0;
}
}
}

void createRandomAddress()
{
unsigned int rand, rand2;
do
{
rand = TI_getRandomIntegerFromVLO(); // first byte can not be 0x00 of 0xFF
}
while( (rand & 0xFF00)==0xFF00 || (rand & 0xFF00)==0x0000 );
rand2 = TI_getRandomIntegerFromVLO();

BCSCTL1 = CALBC1_1MHZ; // Set DCO to 1MHz
DCOCTL = CALDCO_1MHZ;
FCTL2 = FWKEY + FSSEL0 + FN1; // MCLK/3 for Flash Timing Generator
FCTL3 = FWKEY + LOCKA; // Clear LOCK & LOCKA bits
FCTL1 = FWKEY + WRT; // Set WRT bit for write operation

Flash_Addr[0]=(rand>>8) & 0xFF;
Flash_Addr[1]=rand & 0xFF;
Flash_Addr[2]=(rand2>>8) & 0xFF;
Flash_Addr[3]=rand2 & 0xFF;

FCTL1 = FWKEY; // Clear WRT bit
FCTL3 = FWKEY + LOCKA + LOCK; // Set LOCK & LOCKA bit
}

/*------------------------------------------------------------------------------
* ADC10 interrupt service routine
*----------------------------------------------------------------------------*/
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR(void)
{
__bic_SR_register_on_exit(CPUOFF); // Clear CPUOFF bit from 0(SR)
}

/*------------------------------------------------------------------------------
* Timer A0 interrupt service routine
*----------------------------------------------------------------------------*/
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A (void)
{
sSelfMeasureSem = 1;
__bic_SR_register_on_exit(LPM3_bits); // Clear LPM3 bit from 0(SR)
}