Merge pull request #295 from kwagyeman/sensor_fixes

Add auto gain control ceiling value to be settable by the auto gain
This commit is contained in:
Ibrahim Abd Elkader 2017-12-31 15:05:50 +02:00 committed by GitHub
commit 07b238acf8
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10 changed files with 86 additions and 13 deletions

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@ -101,6 +101,7 @@
#define MT9V034_VERTICAL_BLANKING_A (0x06)
#define MT9V034_COARSE_SHUTTER_WIDTH_TOTAL_A (0x0B)
#define MT9V034_ANALOG_GAIN_CONTROL (0x35)
#define MT9V034_MAX_GAIN (0xAB)
#define MT9V034_FINE_SHUTTER_WIDTH_TOTAL_A (0xD5)
static int reset(sensor_t *sensor)
@ -202,17 +203,22 @@ static int set_colorbar(sensor_t *sensor, int enable)
return 0;
}
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db, float gain_db_ceiling)
{
uint16_t reg, agc_gain;
uint16_t reg;
int ret = cambus_readw(sensor->slv_addr, MT9V034_AEC_AGC_ENABLE, &reg);
ret |= cambus_writew(sensor->slv_addr, MT9V034_AEC_AGC_ENABLE, (reg & (~MT9V034_AGC_ENABLE)) | ((enable != 0) ? MT9V034_AGC_ENABLE : 0));
if ((enable == 0) && (gain_db >= 0)) {
int gain = IM_MAX(IM_MIN(fast_roundf(fast_expf((gain_db / 20.0) * fast_log(10.0)) * 16.0), 127), 0);
ret |= cambus_readw(sensor->slv_addr, MT9V034_ANALOG_GAIN_CONTROL, &agc_gain);
ret |= cambus_writew(sensor->slv_addr, MT9V034_ANALOG_GAIN_CONTROL, (agc_gain & 0xFF80) | gain);
ret |= cambus_readw(sensor->slv_addr, MT9V034_ANALOG_GAIN_CONTROL, &reg);
ret |= cambus_writew(sensor->slv_addr, MT9V034_ANALOG_GAIN_CONTROL, (reg & 0xFF80) | gain);
} else if ((enable != 0) && (gain_db_ceiling >= 0)) {
int gain_ceiling = IM_MAX(IM_MIN(fast_roundf(fast_expf((gain_db_ceiling / 20.0) * fast_log(10.0)) * 16.0), 127), 16);
ret |= cambus_readw(sensor->slv_addr, MT9V034_MAX_GAIN, &reg);
ret |= cambus_writew(sensor->slv_addr, MT9V034_MAX_GAIN, (reg & 0xFF80) | gain_ceiling);
}
return ret;

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@ -602,7 +602,7 @@ static int set_colorbar(sensor_t *sensor, int enable)
return cambus_writeb(sensor->slv_addr, COM7, reg) | ret;
}
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db, float gain_db_ceiling)
{
uint8_t reg;
int ret = cambus_readb(sensor->slv_addr, BANK_SEL, &reg);
@ -624,6 +624,11 @@ static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
}
ret |= cambus_writeb(sensor->slv_addr, GAIN, (gain_hi << 4) | (gain_lo << 0));
} else if ((enable != 0) && (gain_db_ceiling >= 0)) {
float gain_ceiling = IM_MAX(IM_MIN(fast_expf((gain_db_ceiling / 20.0) * fast_log(10.0)), 128.0), 1.0);
ret |= cambus_readb(sensor->slv_addr, COM9, &reg);
ret |= cambus_writeb(sensor->slv_addr, COM9, (reg & 0x1F) | ((fast_ceilf(fast_log2(gain_ceiling)) - 1) << 5));
}
return ret;

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@ -352,7 +352,7 @@ static int set_colorbar(sensor_t *sensor, int enable)
return cambus_writeb(sensor->slv_addr, DSP_CTRL3, reg) | ret;
}
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db, float gain_db_ceiling)
{
uint8_t reg;
int ret = cambus_readb(sensor->slv_addr, COM8, &reg);
@ -372,6 +372,11 @@ static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
}
ret |= cambus_writeb(sensor->slv_addr, GAIN, (gain_hi << 4) | (gain_lo << 0));
} else if ((enable != 0) && (gain_db_ceiling >= 0)) {
float gain_ceiling = IM_MAX(IM_MIN(fast_expf((gain_db_ceiling / 20.0) * fast_log(10.0)), 32.0), 1.0);
ret |= cambus_readb(sensor->slv_addr, COM9, &reg);
ret |= cambus_writeb(sensor->slv_addr, COM9, (reg & 0x8F) | ((fast_ceilf(fast_log2(gain_ceiling)) - 1) << 4));
}
return ret;

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@ -328,7 +328,7 @@ static int set_gainceiling(sensor_t *sensor, gainceiling_t gainceiling)
return 0;
}
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
static int set_auto_gain(sensor_t *sensor, int enable, float gain_db, float gain_db_ceiling)
{
uint8_t reg;
int ret = cambus_readb(sensor->slv_addr, REG_COM8, &reg);
@ -350,6 +350,11 @@ static int set_auto_gain(sensor_t *sensor, int enable, float gain_db)
ret |= cambus_writeb(sensor->slv_addr, REG_GAIN, ((gain_hi & 0x0F) << 4) | (gain_lo << 0));
ret |= cambus_readb(sensor->slv_addr, REG_VREF, &reg);
ret |= cambus_writeb(sensor->slv_addr, REG_VREF, ((gain_hi & 0x30) << 2) | (reg & 0x3F));
} else if ((enable != 0) && (gain_db_ceiling >= 0)) {
float gain_ceiling = IM_MAX(IM_MIN(fast_expf((gain_db_ceiling / 20.0) * fast_log(10.0)), 128.0), 1.0);
ret |= cambus_readb(sensor->slv_addr, REG_COM9, &reg);
ret |= cambus_writeb(sensor->slv_addr, REG_COM9, (reg & 0x8F) | ((fast_ceilf(fast_log2(gain_ceiling)) - 1) << 4));
}
return ret;

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@ -345,8 +345,10 @@ static mp_obj_t py_sensor_set_colorbar(mp_obj_t enable) {
}
static mp_obj_t py_sensor_set_auto_gain(uint n_args, const mp_obj_t *args, mp_map_t *kw_args) {
int enable = mp_obj_get_int(args[0]);
float gain_db = py_helper_lookup_float(kw_args, MP_OBJ_NEW_QSTR(MP_QSTR_gain_db), -1);
if (sensor_set_auto_gain(mp_obj_get_int(args[0]), gain_db) != 0) {
float gain_db_ceiling = py_helper_lookup_float(kw_args, MP_OBJ_NEW_QSTR(MP_QSTR_gain_db_ceiling), -1);
if (sensor_set_auto_gain(enable, gain_db, gain_db_ceiling) != 0) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "Sensor control failed!"));
}
return mp_const_none;

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@ -223,6 +223,7 @@ Q(set_quality)
Q(set_colorbar)
Q(set_auto_gain)
Q(gain_db)
Q(gain_db_ceiling)
Q(get_gain_db)
Q(set_auto_exposure)
Q(exposure_us)

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@ -525,11 +525,11 @@ int sensor_set_colorbar(int enable)
return 0;
}
int sensor_set_auto_gain(int enable, float gain_db)
int sensor_set_auto_gain(int enable, float gain_db, float gain_db_ceiling)
{
/* call the sensor specific function */
if (sensor.set_auto_gain == NULL
|| sensor.set_auto_gain(&sensor, enable, gain_db) != 0) {
|| sensor.set_auto_gain(&sensor, enable, gain_db, gain_db_ceiling) != 0) {
/* operation not supported */
return -1;
}

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@ -135,7 +135,7 @@ typedef struct _sensor {
int (*set_gainceiling) (sensor_t *sensor, gainceiling_t gainceiling);
int (*set_quality) (sensor_t *sensor, int quality);
int (*set_colorbar) (sensor_t *sensor, int enable);
int (*set_auto_gain) (sensor_t *sensor, int enable, float gain_db);
int (*set_auto_gain) (sensor_t *sensor, int enable, float gain_db, float gain_db_ceiling);
int (*get_gain_db) (sensor_t *sensor, float *gain_db);
int (*set_auto_exposure) (sensor_t *sensor, int enable, int exposure_us);
int (*get_exposure_us) (sensor_t *sensor, int *exposure_us);
@ -202,7 +202,7 @@ int sensor_set_quality(int qs);
int sensor_set_colorbar(int enable);
// Enable auto gain or set value manually.
int sensor_set_auto_gain(int enable, float gain_db);
int sensor_set_auto_gain(int enable, float gain_db, float gain_db_ceiling);
// Get the gain value.
int sensor_get_gain_db(float *gain_db);

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@ -0,0 +1,49 @@
# Sensor Auto Gain Control
#
# This example shows off how to control the sensor's gain
# using the automatic gain control algorithm.
# What's the difference between gain and exposure control?
#
# Well, by increasing the exposure time for the image you're getting more
# light on the camera. This gives you the best signal to noise ratio. You
# in general always want to increase the expsoure time... except, when you
# increase the exposure time you decrease the maximum possible frame rate
# and if anything moves in the image it will start to blur more with a
# higher exposure time. Gain control allows you to increase the output per
# pixel using analog and digital multipliers... however, it also amplifies
# noise. So, it's best to let the exposure increase as much as possible
# and then use gain control to make up any remaining ground.
# We can achieve the above by setting a gain ceiling on the automatic
# gain control algorithm. Once this is set the algorithm will have to
# increase the exposure time to meet any gain needs versus using gain
# to do so. However, this comes at the price of the exposure time varying
# more when the lighting changes versus the exposure being constant and
# the gain changing.
import sensor, image, time
sensor.reset() # Reset and initialize the sensor.
sensor.set_pixformat(sensor.RGB565) # Set pixel format to RGB565 (or GRAYSCALE)
sensor.set_framesize(sensor.QVGA) # Set frame size to QVGA (320x240)
# The gain db ceiling maxes out at about 24 db for the OV7725 sensor.
sensor.set_auto_gain(True, gain_db_ceiling = 16.0) # Default gain.
# Note! If you set the gain ceiling to low without adjusting the exposure control
# target value then you'll just get a lot of oscillation from the exposure
# control if it's on.
sensor.skip_frames(time = 2000) # Wait for settings take effect.
clock = time.clock() # Create a clock object to track the FPS.
# Note! You can't read the gain/exposure values in the loop while AGC/AEC is on
# since we have to disable the sensor auto control in order to read the values
# (they are spread accross registers and can't be read atomically if the control is on).
while(True):
clock.tick() # Update the FPS clock.
img = sensor.snapshot() # Take a picture and return the image.
print(clock.fps()) # Note: OpenMV Cam runs about half as fast when connected
# to the IDE. The FPS should increase once disconnected.

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@ -1,4 +1,4 @@
# Sensor Gain Control
# Sensor Manual Gain Control
#
# This example shows off how to control the camera sensor's
# gain manually versus letting auto gain control run.