diff --git a/bme680.c b/bme680.c
index 0b2bc80..6d845d4 100644
--- a/bme680.c
+++ b/bme680.c
@@ -18,7 +18,6 @@ static int set_spi_page(bme680_t *bme680, uint8_t no);
 
 /********************************************************************/
 static int write_dev(bme680_t *bme680, uint8_t reg, uint8_t value) {
-
 	if (BME680_IS_SPI(bme680->mode)) {
 		check_spi_page(bme680, reg);
 		reg &= 0x7F;
@@ -29,7 +28,6 @@ static int write_dev(bme680_t *bme680, uint8_t reg, uint8_t value) {
 
 /********************************************************************/
 static int read_dev(bme680_t *bme680, uint8_t reg, uint8_t *dst, uint32_t size) {
-
 	if (BME680_IS_SPI(bme680->mode)) {
 		check_spi_page(bme680, reg);
 		reg |= 0x80; 
@@ -57,7 +55,6 @@ static int set_spi_page(bme680_t *bme680, uint8_t page_no) {
 
 /********************************************************************/
 static int read_id(bme680_t *bme680, uint8_t *id) {
-
 	uint8_t id_reg;
 
 	/* force spi page 0. special case */
@@ -73,8 +70,27 @@ static int read_id(bme680_t *bme680, uint8_t *id) {
 }
 
 /********************************************************************/
-int bme680_init(bme680_t *bme680, uint8_t mode) {
+/* write local setpoint index to device, must not be running */
+int bme680_write_setpoint_index(bme680_t *bme680) {
+	/* setpoint (0 thru 9) bits 0,1,2,3 and run_gas bit 4 */
+	uint8_t ctrl_gas_1 = (bme680->setpoint & 0x0F) | (1 << 4);
+	return write_dev(bme680, REG_CTRL_GAS_1, ctrl_gas_1);
+}
 
+/********************************************************************/
+/* read the currently selected heater setpoint index on the device */
+int bme680_read_setpoint_index(bme680_t *bme680, uint8_t *index) {
+	uint8_t meas_status;
+	int err = 0;
+
+	err |= read_dev(bme680, REG_MEAS_STATUS, &meas_status, 1);
+	*index = (meas_status) & 0x0F;
+
+	return err;
+}
+
+/********************************************************************/
+int bme680_init(bme680_t *bme680, uint8_t mode) {
 	uint8_t id;
 	int i;
 
@@ -82,12 +98,12 @@ int bme680_init(bme680_t *bme680, uint8_t mode) {
 	bme680->spi_page = 0; 
 	bme680->gas_valid = 0;
 	bme680->heat_stab = 0;
+	bme680->setpoint = 0;
 
 	if (bme680->dev.init() != 0) {
 		return 1;
 	}
 
-
 	if (read_id(bme680, &id) != 0) {
 		return 1;
 	}
@@ -139,7 +155,6 @@ int bme680_reset(bme680_t *bme680) {
 /********************************************************************/
 /* configure device */
 int bme680_configure(bme680_t *bme680) {
-
 	uint8_t meas, hum, filter, ctrl_gas1, ctrl_gas0, err;
 	int i;
 	meas = hum = filter = err = 0;
@@ -170,7 +185,7 @@ int bme680_configure(bme680_t *bme680) {
 		err |= write_dev(bme680, 0x59 - i, bme680->cfg.idac_heat[9 - i]);	
 	}
 
-	ctrl_gas1 = bme680->cfg.setpoint | (1 << 4);
+	ctrl_gas1 = bme680->setpoint | (1 << 4);
 	ctrl_gas0 = 0; /* := (1 << 3) to turn off current going to heater */
 
 	err |= write_dev(bme680, REG_CTRL_GAS_1, ctrl_gas1);
@@ -183,7 +198,6 @@ SKIP_GAS:
 /********************************************************************/
 /* To start forced mode, you just have to set the lsb=1 of REG_CTRL_MEAS */
 int bme680_start(bme680_t *bme680) {
-
 	int err = 0;
 	uint8_t meas;
 	meas = bme680->cfg.meas | 1;
@@ -192,11 +206,8 @@ int bme680_start(bme680_t *bme680) {
 }
 
 /********************************************************************/
-/* blocks until the device all scheduled conversions are done. 
- * don't call out of order.
- */
+/* blocks until all scheduled conversions on the device are done. */
 int bme680_poll(bme680_t *bme680) {
-
 	uint8_t meas_status = 0;
 	uint8_t gas_measuring = 0;
 	uint8_t any_measuring = 0;
@@ -205,7 +216,7 @@ int bme680_poll(bme680_t *bme680) {
 
 	do {
 		usleep(5000); /* 5 ms */
-		err |= read_dev(bme680, REG_EAS_STATUS, &meas_status, 1);
+		err |= read_dev(bme680, REG_MEAS_STATUS, &meas_status, 1);
 		gas_measuring = (meas_status >> 6) & 1;
 		any_measuring = (meas_status >> 5) & 1;
 
@@ -217,7 +228,6 @@ int bme680_poll(bme680_t *bme680) {
 /********************************************************************/
 /* assume start'd and poll'd */
 int bme680_read(bme680_t *bme680) {
-
 	/* begin by reading ADCs */
 	uint8_t buffer[3] = {0, 0 ,0};
 	int err = 0;
@@ -231,7 +241,6 @@ int bme680_read(bme680_t *bme680) {
 	err |= read_dev(bme680, 0x25, buffer, 2);
 	bme680->adc.hum = (buffer[0] << 8) | buffer[1];
 
-
 	/* adc readings are only 20-bit when the IIR filter is enabled.
 	 * otherwise, it depends on the oversample settings.
 	 * note: humidity is not IIR filtered, and always 16-bit.
@@ -302,7 +311,6 @@ static int const_array2_int[16] = {
 /********************************************************************/
 /********************************************************************/
 static void calc_temp_comp_1 (bme680_t *bme680) {
-
 	double var1, var2, temp_comp;
 
 	var1 = (((double)bme680->adc.temp / 16384.0) - ((double)bme680->cal.par_t1 / 1024.0)) * 
@@ -317,7 +325,6 @@ static void calc_temp_comp_1 (bme680_t *bme680) {
 
 /********************************************************************/
 static void calc_temp_comp_2 (bme680_t *bme680) {
-
 	int32_t var1, var2, var3, temp_comp;
 
 	var1 = ((int32_t)bme680->adc.temp >> 3) - ((int32_t) bme680->cal.par_t1 << 1);
@@ -337,10 +344,8 @@ static void calc_temp_comp (bme680_t *bme680) {
 	}
 }
 
-/********************************************************************/
 /********************************************************************/
 static void calc_press_comp_1 (bme680_t *bme680) {
-
 	double var1, var2, var3, press_comp;
 
 	var1 = ((double)bme680->fcomp.tfine / 2.0) - 64000.0;
@@ -362,7 +367,6 @@ static void calc_press_comp_1 (bme680_t *bme680) {
 
 /********************************************************************/
 static void calc_press_comp_2 (bme680_t *bme680 )  {
-
 	int32_t var1, var2, var3, press_comp;
 
 	var1 = ((int32_t)bme680->icomp.tfine >> 1) - 64000;
@@ -397,10 +401,8 @@ static void calc_press_comp (bme680_t *bme680) {
 	}
 }
 
-/********************************************************************/
 /********************************************************************/
 static void calc_hum_comp_1 (bme680_t *bme680) {
-	
 	double var1, var2, var3, var4, hum_comp, temp_comp;
 
 	temp_comp = bme680->fcomp.temp;
@@ -417,7 +419,6 @@ static void calc_hum_comp_1 (bme680_t *bme680) {
 
 /********************************************************************/
 static void calc_hum_comp_2 (bme680_t *bme680) {
-
 	int32_t  var1, var2, var3, var4, var5, var6, temp_scaled, hum_comp;
 	
 	temp_scaled = (int32_t)bme680->icomp.temp;
@@ -448,7 +449,6 @@ static void calc_hum_comp (bme680_t *bme680) {
 /********************************************************************/
 // TODO: read one big contiguous block
 int bme680_calibrate(bme680_t *bme680) {
-
 	uint8_t buffer[3] = {0, 0 ,0};
 	int err = 0;
 
@@ -540,7 +540,6 @@ int bme680_calibrate(bme680_t *bme680) {
 	return err;
 }
 
-/********************************************************************/
 /********************************************************************/
 static void calc_gas_res_1(bme680_t *bme680) {
 	double var1, gas_res;
@@ -571,7 +570,6 @@ static void calc_gas_res(bme680_t *bme680) {
 	}
 }
 
-/********************************************************************/
 /********************************************************************/
 void bme680_print_calibration (bme680_t *bme680) {
 	printf("par_t1: %d\n", bme680->cal.par_t1);
@@ -602,6 +600,7 @@ void bme680_print_calibration (bme680_t *bme680) {
 	printf("res_heat_val: %d\n", bme680->cal.res_heat_val);
 }
 
+/********************************************************************/
 static uint8_t calc_target_1(bme680_t *bme680, double target, double ambient) {
 	double var1, var2, var3, var4, var5;
 	uint8_t res_heat;
@@ -616,6 +615,7 @@ static uint8_t calc_target_1(bme680_t *bme680, double target, double ambient) {
 	return res_heat;
 }
 
+/********************************************************************/
 static uint8_t calc_target_2(bme680_t *bme680, double target, double ambient) {
 	int32_t var1, var2, var3, var4, var5, res_heat_x100;
 	uint8_t res_heat;
@@ -631,6 +631,7 @@ static uint8_t calc_target_2(bme680_t *bme680, double target, double ambient) {
 	return res_heat;
 }
 
+/********************************************************************/
 uint8_t bme680_calc_target(bme680_t *bme680, double target, double ambient) {
 	if (BME680_IS_FLOAT(bme680->mode)) {
 		return calc_target_1(bme680, target, ambient);
diff --git a/bme680.h b/bme680.h
index 9fb5389..87b1865 100644
--- a/bme680.h
+++ b/bme680.h
@@ -94,7 +94,6 @@ struct bme680_config {
 	uint8_t osrs_p;
 	uint8_t osrs_h;
 	uint8_t filter;
-	uint8_t setpoint;
 	uint8_t idac_heat[10];
 	uint8_t res_heat[10];
 	uint8_t gas_wait[10];
@@ -134,6 +133,7 @@ struct bme680 {
 	struct bme680_config cfg;
 	struct bme680_adc adc;
 	uint8_t mode;
+	uint8_t setpoint;
 	uint8_t spi_page; 
 	uint8_t gas_valid;
 	uint8_t heat_stab;
@@ -150,6 +150,8 @@ int bme680_configure(bme680_t *bme680);
 int bme680_start(bme680_t *bme680);
 int bme680_poll(bme680_t *bme680);
 int bme680_read(bme680_t *bme680);
+int bme680_write_setpoint_index(bme680_t *bme680);
+int bme680_read_setpoint_index(bme680_t *bme680, uint8_t *index);
 
 uint8_t bme680_calc_target(bme680_t *bme680, double target, double ambient);
 
diff --git a/bst-bme680-ds001.pdf b/datasheet.pdf
similarity index 100%
rename from bst-bme680-ds001.pdf
rename to datasheet.pdf
diff --git a/example/README.md b/example/README.md
new file mode 100644
index 0000000..ead86ba
--- /dev/null
+++ b/example/README.md
@@ -0,0 +1,124 @@
+# bme680/example
+
+
+iterate\_setpoint.c
+```
+heater_target=300.0, ambient_temp=19.0
+first few setpoints have heater_target=380
+[Setpoint 0] temp=18.37°C, press=1005.54 mbar, hum=67.03 %RH, gas_res=10749063.67 gv=1 hs=0
+[Setpoint 1] temp=18.37°C, press=1005.54 mbar, hum=67.06 %RH, gas_res=7906336.09 gv=1 hs=0
+[Setpoint 2] temp=18.38°C, press=1005.54 mbar, hum=67.07 %RH, gas_res=6449438.20 gv=1 hs=0
+[Setpoint 3] temp=18.38°C, press=1005.54 mbar, hum=67.06 %RH, gas_res=5329619.31 gv=1 hs=0
+[Setpoint 4] temp=18.39°C, press=1005.54 mbar, hum=67.03 %RH, gas_res=4701064.70 gv=1 hs=0
+[Setpoint 5] temp=18.40°C, press=1005.54 mbar, hum=66.99 %RH, gas_res=4242424.24 gv=1 hs=0
+[Setpoint 6] temp=18.41°C, press=1005.54 mbar, hum=66.93 %RH, gas_res=7667.94 gv=1 hs=1
+[Setpoint 7] temp=18.43°C, press=1005.54 mbar, hum=66.92 %RH, gas_res=8942.73 gv=1 hs=1
+[Setpoint 8] temp=18.45°C, press=1005.54 mbar, hum=66.89 %RH, gas_res=9496.84 gv=1 hs=1
+[Setpoint 9] temp=18.47°C, press=1005.54 mbar, hum=66.79 %RH, gas_res=9804.77 gv=1 hs=1
+```
+
+continuous.c
+```
+heater_target=300.0, ambient_temp=19.0
+temp=20.73°C, press=1005.41 mbar, hum=54.19 %RH, gas_res=9537.32
+temp=20.74°C, press=1005.41 mbar, hum=54.42 %RH, gas_res=9813.37
+temp=20.75°C, press=1005.41 mbar, hum=54.61 %RH, gas_res=9813.37
+temp=20.78°C, press=1005.41 mbar, hum=54.76 %RH, gas_res=9804.77
+temp=20.80°C, press=1005.41 mbar, hum=54.87 %RH, gas_res=9813.37
+temp=20.83°C, press=1005.41 mbar, hum=54.95 %RH, gas_res=9787.61
+temp=20.85°C, press=1005.41 mbar, hum=54.99 %RH, gas_res=9770.52
+temp=20.88°C, press=1005.42 mbar, hum=55.01 %RH, gas_res=9770.52
+temp=20.91°C, press=1005.42 mbar, hum=55.00 %RH, gas_res=9744.99
+temp=20.94°C, press=1005.42 mbar, hum=54.97 %RH, gas_res=9711.16
+temp=20.98°C, press=1005.42 mbar, hum=54.91 %RH, gas_res=9711.16
+temp=21.01°C, press=1005.42 mbar, hum=54.84 %RH, gas_res=9694.33
+temp=21.04°C, press=1005.42 mbar, hum=54.76 %RH, gas_res=9685.94
+temp=21.07°C, press=1005.42 mbar, hum=54.67 %RH, gas_res=9677.56
+temp=21.11°C, press=1005.42 mbar, hum=54.56 %RH, gas_res=9669.20
+temp=21.14°C, press=1005.42 mbar, hum=54.45 %RH, gas_res=9669.20
+temp=21.18°C, press=1005.42 mbar, hum=54.34 %RH, gas_res=9660.85
+temp=21.21°C, press=1005.42 mbar, hum=54.22 %RH, gas_res=9644.19
+temp=21.24°C, press=1005.43 mbar, hum=54.09 %RH, gas_res=9652.51
+temp=21.28°C, press=1005.43 mbar, hum=53.96 %RH, gas_res=9644.19
+temp=21.31°C, press=1005.43 mbar, hum=53.83 %RH, gas_res=9627.59
+temp=21.35°C, press=1005.43 mbar, hum=53.70 %RH, gas_res=9611.05
+temp=21.38°C, press=1005.43 mbar, hum=53.55 %RH, gas_res=9619.32
+temp=21.42°C, press=1005.43 mbar, hum=53.42 %RH, gas_res=9619.32
+temp=21.45°C, press=1005.43 mbar, hum=53.30 %RH, gas_res=9611.05
+temp=21.49°C, press=1005.43 mbar, hum=53.16 %RH, gas_res=9602.80
+temp=21.52°C, press=1005.44 mbar, hum=53.02 %RH, gas_res=9586.35
+temp=21.56°C, press=1005.44 mbar, hum=52.90 %RH, gas_res=9602.80
+temp=21.59°C, press=1005.44 mbar, hum=52.76 %RH, gas_res=9569.95
+temp=21.63°C, press=1005.44 mbar, hum=52.62 %RH, gas_res=9586.35
+temp=21.66°C, press=1005.44 mbar, hum=52.51 %RH, gas_res=9569.95
+temp=21.70°C, press=1005.44 mbar, hum=52.38 %RH, gas_res=9569.95
+temp=21.73°C, press=1005.44 mbar, hum=52.26 %RH, gas_res=9561.77
+temp=21.77°C, press=1005.44 mbar, hum=52.13 %RH, gas_res=9553.61
+temp=21.80°C, press=1005.45 mbar, hum=52.00 %RH, gas_res=9553.61
+temp=21.84°C, press=1005.45 mbar, hum=51.89 %RH, gas_res=9553.61
+temp=21.87°C, press=1005.45 mbar, hum=51.77 %RH, gas_res=9553.61
+temp=21.91°C, press=1005.45 mbar, hum=51.65 %RH, gas_res=9553.61
+temp=21.94°C, press=1005.45 mbar, hum=51.55 %RH, gas_res=9537.32
+temp=21.98°C, press=1005.45 mbar, hum=51.41 %RH, gas_res=9521.09
+temp=22.01°C, press=1005.45 mbar, hum=51.31 %RH, gas_res=9529.20
+temp=22.04°C, press=1005.45 mbar, hum=51.19 %RH, gas_res=9529.20
+temp=22.08°C, press=1005.45 mbar, hum=51.08 %RH, gas_res=9529.20
+temp=22.11°C, press=1005.45 mbar, hum=50.97 %RH, gas_res=9512.99
+temp=22.15°C, press=1005.46 mbar, hum=50.86 %RH, gas_res=9504.91
+temp=22.18°C, press=1005.46 mbar, hum=50.76 %RH, gas_res=9504.91
+temp=22.22°C, press=1005.46 mbar, hum=50.64 %RH, gas_res=9512.99
+temp=22.25°C, press=1005.46 mbar, hum=50.54 %RH, gas_res=9504.91
+temp=22.28°C, press=1005.46 mbar, hum=50.44 %RH, gas_res=9488.79
+temp=22.32°C, press=1005.46 mbar, hum=50.34 %RH, gas_res=9488.79
+temp=22.35°C, press=1005.46 mbar, hum=50.24 %RH, gas_res=9480.75
+temp=22.39°C, press=1005.46 mbar, hum=50.15 %RH, gas_res=9480.75
+temp=22.42°C, press=1005.46 mbar, hum=50.05 %RH, gas_res=9472.72
+temp=22.45°C, press=1005.47 mbar, hum=49.94 %RH, gas_res=9464.71
+temp=22.49°C, press=1005.47 mbar, hum=49.86 %RH, gas_res=9472.72
+temp=22.52°C, press=1005.47 mbar, hum=49.76 %RH, gas_res=9464.71
+temp=22.55°C, press=1005.47 mbar, hum=49.67 %RH, gas_res=9480.75
+temp=22.59°C, press=1005.47 mbar, hum=49.58 %RH, gas_res=9456.71
+temp=22.62°C, press=1005.47 mbar, hum=49.49 %RH, gas_res=9472.72
+temp=22.65°C, press=1005.47 mbar, hum=49.41 %RH, gas_res=9456.71
+temp=22.68°C, press=1005.47 mbar, hum=49.33 %RH, gas_res=9456.71
+temp=22.72°C, press=1005.47 mbar, hum=49.24 %RH, gas_res=9432.79
+temp=22.75°C, press=1005.47 mbar, hum=49.15 %RH, gas_res=9432.79
+temp=22.78°C, press=1005.47 mbar, hum=49.08 %RH, gas_res=9440.75
+temp=22.81°C, press=1005.47 mbar, hum=49.00 %RH, gas_res=9440.75
+temp=22.85°C, press=1005.48 mbar, hum=48.92 %RH, gas_res=9432.79
+temp=22.88°C, press=1005.48 mbar, hum=48.84 %RH, gas_res=9432.79
+temp=22.91°C, press=1005.48 mbar, hum=48.77 %RH, gas_res=9416.91
+temp=22.94°C, press=1005.48 mbar, hum=48.71 %RH, gas_res=9440.75
+temp=22.97°C, press=1005.48 mbar, hum=48.63 %RH, gas_res=9440.75
+temp=23.00°C, press=1005.48 mbar, hum=48.56 %RH, gas_res=9432.79
+temp=23.04°C, press=1005.48 mbar, hum=48.50 %RH, gas_res=9408.99
+temp=23.07°C, press=1005.48 mbar, hum=48.42 %RH, gas_res=9424.84
+temp=23.10°C, press=1005.48 mbar, hum=48.36 %RH, gas_res=9416.91
+temp=23.13°C, press=1005.48 mbar, hum=48.29 %RH, gas_res=9408.99
+temp=23.16°C, press=1005.48 mbar, hum=48.24 %RH, gas_res=9408.99
+temp=23.19°C, press=1005.48 mbar, hum=48.17 %RH, gas_res=9408.99
+temp=23.22°C, press=1005.48 mbar, hum=48.12 %RH, gas_res=9416.91
+temp=23.25°C, press=1005.48 mbar, hum=48.05 %RH, gas_res=9416.91
+temp=23.28°C, press=1005.49 mbar, hum=48.00 %RH, gas_res=9416.91
+temp=23.31°C, press=1005.49 mbar, hum=47.94 %RH, gas_res=9401.09
+temp=23.34°C, press=1005.49 mbar, hum=47.89 %RH, gas_res=9385.32
+temp=23.37°C, press=1005.49 mbar, hum=47.84 %RH, gas_res=9385.32
+temp=23.40°C, press=1005.49 mbar, hum=47.78 %RH, gas_res=9401.09
+temp=23.43°C, press=1005.49 mbar, hum=47.74 %RH, gas_res=9393.19
+temp=23.46°C, press=1005.49 mbar, hum=47.68 %RH, gas_res=9385.32
+temp=23.49°C, press=1005.49 mbar, hum=47.64 %RH, gas_res=9377.45
+temp=23.52°C, press=1005.49 mbar, hum=47.58 %RH, gas_res=9385.32
+temp=23.54°C, press=1005.49 mbar, hum=47.54 %RH, gas_res=9377.45
+temp=23.57°C, press=1005.49 mbar, hum=47.49 %RH, gas_res=9385.32
+temp=23.60°C, press=1005.49 mbar, hum=47.45 %RH, gas_res=9385.32
+temp=23.63°C, press=1005.49 mbar, hum=47.40 %RH, gas_res=9377.45
+temp=23.66°C, press=1005.49 mbar, hum=47.36 %RH, gas_res=9369.60
+temp=23.69°C, press=1005.49 mbar, hum=47.32 %RH, gas_res=9361.76
+temp=23.71°C, press=1005.49 mbar, hum=47.28 %RH, gas_res=9377.45
+temp=23.74°C, press=1005.49 mbar, hum=47.24 %RH, gas_res=9369.60
+temp=23.77°C, press=1005.49 mbar, hum=47.20 %RH, gas_res=9377.45
+temp=23.80°C, press=1005.50 mbar, hum=47.16 %RH, gas_res=9385.32
+temp=23.82°C, press=1005.50 mbar, hum=47.13 %RH, gas_res=9377.45
+temp=23.85°C, press=1005.50 mbar, hum=47.08 %RH, gas_res=9353.93
+temp=23.88°C, press=1005.50 mbar, hum=47.04 %RH, gas_res=9353.93
+```
diff --git a/example/continuous.c b/example/continuous.c
new file mode 100644
index 0000000..5919d2a
--- /dev/null
+++ b/example/continuous.c
@@ -0,0 +1,99 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "bme680.h"
+#include "i2c.h"
+#include "spi.h"
+
+#define AMBIENT_TEMP_GUESS 19.0
+#define HEATER_TARGET 300.0
+
+void pretty_print(bme680_t *bme680);
+
+int main(void) {
+	
+	bme680_t bme680;
+	uint8_t mode;
+	int counter;
+
+	bme680.dev.init   = spi_init;
+	bme680.dev.read   = spi_read;
+	bme680.dev.write  = spi_write;
+	bme680.dev.deinit = spi_deinit;
+
+	mode = BME680_MODE_FLOAT | BME680_SPI | BME680_ENABLE_GAS;
+
+	if (bme680_init(&bme680, mode) != 0) {
+		fprintf(stderr, "bme680_init()\n");
+		exit(EXIT_FAILURE);
+	}
+
+	bme680_reset(&bme680);
+
+	if (bme680_calibrate(&bme680) != 0) {
+		fprintf(stderr, "bme680_calibrate()\n");
+		bme680_deinit(&bme680);
+		exit(EXIT_FAILURE);
+	}
+
+	bme680.cfg.osrs_t = BME680_OVERSAMPLE_X16;
+	bme680.cfg.osrs_p = BME680_OVERSAMPLE_X16;
+	bme680.cfg.osrs_h = BME680_OVERSAMPLE_X8;
+	bme680.cfg.filter = BME680_IIR_COEFF_127;
+
+	/* only 1 setpoint */
+	bme680.cfg.res_heat[0] = bme680_calc_target(&bme680, HEATER_TARGET, AMBIENT_TEMP_GUESS);
+	bme680.cfg.idac_heat[0] = BME680_IDAC(100);
+	bme680.cfg.gas_wait[0] = BME680_GAS_WAIT(50, BME680_GAS_WAIT_X4);
+
+	bme680.setpoint = 0;
+	
+	if (bme680_configure(&bme680) != 0) {
+		fprintf(stderr, "bme680_configure()\n");
+		bme680_deinit(&bme680);
+		exit(EXIT_FAILURE);
+	}
+
+	counter = 0;
+
+	printf("heater_target=%.1f, ambient_temp=%.1f\n", HEATER_TARGET, AMBIENT_TEMP_GUESS);
+
+	do {
+		if (bme680_start(&bme680) != 0) {
+			fprintf(stderr, "bme680_start()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		if (bme680_poll(&bme680) != 0) {
+			fprintf(stderr, "bme680_poll()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		if (bme680_read(&bme680) != 0) {
+			fprintf(stderr, "bme680_read()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		pretty_print(&bme680);
+
+	} while(counter++ < 100);
+
+	bme680_deinit(&bme680);
+
+	return 0;
+}
+
+void pretty_print(bme680_t *bme680) {
+
+	double t = bme680->fcomp.temp;
+	double p = bme680->fcomp.press / 100.0;
+	double h = bme680->fcomp.hum;
+	double gr = bme680->fcomp.gas_res;
+
+	printf("temp=%.2f°C, press=%.2f mbar, hum=%.2f %%RH, gas_res=%.2f\n", t, p, h, gr);
+}
diff --git a/example/iterate_setpoint.c b/example/iterate_setpoint.c
new file mode 100644
index 0000000..705b46b
--- /dev/null
+++ b/example/iterate_setpoint.c
@@ -0,0 +1,127 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "bme680.h"
+#include "i2c.h"
+#include "spi.h"
+
+#define AMBIENT_TEMP_GUESS 19.0
+
+/* heater prob won't settle */
+#define HEATER_TARGET_CLEAN_SENSOR 380.0
+
+/* for the "real" measurement */
+#define HEATER_TARGET 300.0
+
+void pretty_print(bme680_t *bme680);
+
+int main(void) {
+	
+	bme680_t bme680;
+	uint8_t mode;
+	int i;
+
+	bme680.dev.init   = spi_init;
+	bme680.dev.read   = spi_read;
+	bme680.dev.write  = spi_write;
+	bme680.dev.deinit = spi_deinit;
+
+	mode = BME680_MODE_FLOAT | BME680_SPI | BME680_ENABLE_GAS;
+
+	if (bme680_init(&bme680, mode) != 0) {
+		fprintf(stderr, "bme680_init()\n");
+		exit(EXIT_FAILURE);
+	}
+
+	bme680_reset(&bme680);
+
+	if (bme680_calibrate(&bme680) != 0) {
+		fprintf(stderr, "bme680_calibrate()\n");
+		bme680_deinit(&bme680);
+		exit(EXIT_FAILURE);
+	}
+
+	bme680.cfg.osrs_t = BME680_OVERSAMPLE_X16;
+	bme680.cfg.osrs_p = BME680_OVERSAMPLE_X16;
+	bme680.cfg.osrs_h = BME680_OVERSAMPLE_X8;
+	bme680.cfg.filter = BME680_IIR_COEFF_127;
+
+	for(i=0; i<10; i++) {
+		/* extra heat to clean the sensor surface. might work ! */
+		if (i < 6) {
+			bme680.cfg.res_heat[i] = bme680_calc_target(&bme680, HEATER_TARGET_CLEAN_SENSOR, AMBIENT_TEMP_GUESS);
+			bme680.cfg.idac_heat[i] = BME680_IDAC(100); //  12.5 mA  
+			bme680.cfg.gas_wait[i] = BME680_GAS_WAIT(50, BME680_GAS_WAIT_X4);
+		} else {
+			bme680.cfg.res_heat[i] = bme680_calc_target(&bme680, HEATER_TARGET, AMBIENT_TEMP_GUESS);
+			bme680.cfg.idac_heat[i] = BME680_IDAC(50);
+			bme680.cfg.gas_wait[i] = BME680_GAS_WAIT(50, BME680_GAS_WAIT_X4);
+		}
+	}
+
+	bme680.setpoint = 0;
+	
+	if (bme680_configure(&bme680) != 0) {
+		fprintf(stderr, "bme680_configure()\n");
+		bme680_deinit(&bme680);
+		exit(EXIT_FAILURE);
+	}
+
+
+	printf("heater_target=%.1f, ambient_temp=%.1f\n", HEATER_TARGET, AMBIENT_TEMP_GUESS);
+	printf("first few setpoints have heater_target=%1.f\n", HEATER_TARGET_CLEAN_SENSOR);
+
+	for(i=0; i<10; i++) {
+
+		bme680.setpoint = i;
+
+		if (bme680_write_setpoint_index(&bme680) != 0) {
+			fprintf(stderr, "bme680_write_setpoint()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		if (bme680_start(&bme680) != 0) {
+			fprintf(stderr, "bme680_start()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		if (bme680_poll(&bme680) != 0) {
+			fprintf(stderr, "bme680_poll()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		if (bme680_read(&bme680) != 0) {
+			fprintf(stderr, "bme680_read()\n");
+			bme680_deinit(&bme680);
+			exit(EXIT_FAILURE);
+		}
+
+		pretty_print(&bme680);
+	}
+
+	bme680_deinit(&bme680);
+
+	return 0;
+}
+
+void pretty_print(bme680_t *bme680) {
+	uint8_t dev_sp;
+
+	bme680_read_setpoint_index(bme680, &dev_sp);
+
+	double t = bme680->fcomp.temp;
+	double p = bme680->fcomp.press / 100.0;
+	double h = bme680->fcomp.hum;
+	double gr = bme680->fcomp.gas_res;
+
+	int gv = bme680->gas_valid;
+	int hs = bme680->heat_stab;
+
+	printf("[Setpoint %d] temp=%.2f°C, press=%.2f mbar, hum=%.2f %%RH, gas_res=%.2f gv=%d hs=%d\n",
+			dev_sp, t, p, h, gr, gv, hs);
+}
diff --git a/i2c.c b/i2c.c
index de21faa..57f65d6 100644
--- a/i2c.c
+++ b/i2c.c
@@ -15,7 +15,6 @@
 static int fd;
 
 int i2c_init(void) {
-
 	fd = open(I2C_DEVICE, O_RDWR);
 	if (fd < 0) {
 		fprintf(stderr, "could not open device: %s\n", I2C_DEVICE);
@@ -33,7 +32,6 @@ int i2c_init(void) {
 
 
 int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
-
 	uint8_t cmd[2] = {reg, 0x00};
 	write(fd, cmd, 2);
 	
@@ -42,12 +40,12 @@ int i2c_read(uint8_t reg, uint8_t *dst, uint32_t size) {
 		return I2C_ERR;
 	
 	}
+
 	return I2C_OK;
 }
 
 
 int i2c_write(uint8_t reg, uint8_t value) {
-	
 	uint8_t cmd[2] = {reg, value};
 	
 	if (write(fd, cmd, 2) != 2) {
@@ -65,3 +63,4 @@ int i2c_deinit(void) {
 
 	return I2C_OK;
 }
+
diff --git a/main.c b/main.c
index 21bd8c0..28b1dea 100644
--- a/main.c
+++ b/main.c
@@ -33,13 +33,13 @@ int main(void) {
 	/*     BME680_MODE_INT   | BME680_I2C; */
 
 
-	/* 3. initialise device, and check its id */
+	/* 3. initialise dev func's, and check device id */
 	if (bme680_init(&bme680, mode) != 0) {
 		fprintf(stderr, "bme680_init()\n");
 		exit(EXIT_FAILURE);
 	}
 
-	/* 4. reset */
+	/* 4. reset device */
 	bme680_reset(&bme680);
 
 	/* 5. read calibration parameters from the device and store in memory */
@@ -61,14 +61,14 @@ int main(void) {
 	/* configuring gas sensor. */
 	/* NB: mode |= BME680_ENABLE_GAS; */
 	/* there are 10 possible heater setpoints */
-	/* they can be though of as frames that define one single gas-resistance measurement */
-	/* they do not carry over or affect eachother in any way. */
+	/* they can be thought of as frames that define one single gas-resistance measurement */
+	/* they do not carry over or affect each other in any way. */
 	for(i=0; i<10; i++) {
 
 		/* calculate a resistance target, based on desired temp, and ambient temp */
 		bme680.cfg.res_heat[i] = bme680_calc_target(&bme680, HEATER_TARGET, AMBIENT_TEMP_GUESS);
 
-		/* initial heating current for the setpoint. Could be useful in cold places.. */
+		/* initial heating current for the setpoint. Could be useful in cold places or short gas_wait durations */
 		/* 7-bit word. Each step/lsb is equiv. to 1/8 mA; so max 16 mA */
 		/* a value of 20 would be equal to 2.5 mA */
 		/* this s.p. field is allowed to be left as 0 if no preload is required. */
@@ -76,14 +76,16 @@ int main(void) {
 
 		/* define the time between the start of heating and start of resistance sensing in this s.p.*/
 		/* Bosch datasheet suggests ~30 - 40ms is usually all that is required to get up to temp. */
+		/* ^ probably with a good idac_heat current but doesn't mention it. */
 		/* 25 * X4 = 100 ms wait before sampling resistance starts. */
-		/* the first value is 6-bit (0...64) with 1 ms step size. */
+		/* the first value is 6-bit (0...63) with 1 ms step size. */
 		bme680.cfg.gas_wait[i] = BME680_GAS_WAIT(25, BME680_GAS_WAIT_X4);
 	}
 
 	/* The BME680 does not cycle between setpoints. They have to be manually set. */
 	/* After each "run", the setpoint has to be changed. */
-	bme680.cfg.setpoint = 0; /* 0 thru 9 */
+	/* the func bme680_write_setpoint_index() will write this field to the dev, without having to reconfigure */
+	bme680.setpoint = 0; /* 0 thru 9 */
 
 	/* 7. write config to device */
 	if (bme680_configure(&bme680) != 0) {
@@ -92,23 +94,22 @@ int main(void) {
 		exit(EXIT_FAILURE);
 	}
 
-
-	/* 8. Start forced measurement. After it finishes, it should remember the previous config. */
+	/* 8. Start forced measurement*. After it finishes, it should remember the previous config. */
+	/*           * = bosch speak for one single T, P, H, GasRes measuring cycle. */
 	if (bme680_start(&bme680) != 0) {
 		fprintf(stderr, "bme680_start()\n");
 		bme680_deinit(&bme680);
 		exit(EXIT_FAILURE);
 	}
 
-
 	/* 9. poll the meas_status register until all scheduled conversions are done */
+	/* this step can be skipped with SPI interrupt (3 wire SPI only. See 5.3.1.1 in datasheet; pg 29) */
 	if (bme680_poll(&bme680) != 0) {
 		fprintf(stderr, "bme680_poll()\n");
 		bme680_deinit(&bme680);
 		exit(EXIT_FAILURE);
 	}
 
-
 	/* 10. read the ADC's and perform a conversion */
 	if (bme680_read(&bme680) != 0) {
 		fprintf(stderr, "bme680_read()\n");
@@ -116,7 +117,6 @@ int main(void) {
 		exit(EXIT_FAILURE);
 	}
 
-
 	/* 11. use data ! */
 	if (BME680_IS_FLOAT(bme680.mode)) {
 		puts("float mode");
diff --git a/registers.h b/registers.h
index ccaeed0..f1546c1 100644
--- a/registers.h
+++ b/registers.h
@@ -63,7 +63,7 @@
 #define REG_PRESS_LSB   0x20
 #define REG_PRESS_MSB   0x1F
 
-#define REG_EAS_STATUS  0x1D
+#define REG_MEAS_STATUS 0x1D