// this gets called when you get an SLA+R
void onRequestService(void){
static uint8_t response[EGG_BUS_MAX_RESPONSE_LENGTH] = { 0 };
uint8_t response_length = 4; // unless it gets overridden 4 is the default
uint8_t sensor_index = 0;
uint8_t sensor_field_offset = 0;
uint16_t address = egg_bus_get_read_address(); // get the address requested in the SLA+W
uint16_t sensor_block_relative_address = address - ((uint16_t) EGG_BUS_SENSOR_BLOCK_BASE_ADDRESS);
uint16_t possible_values[3] = {0,0,0};
uint32_t possible_low_side_resistances[3] = {0,0,0};
uint8_t best_value_index = 0;
uint32_t responseValue = 0;
uint32_t temp = 0;
switch(address){
case EGG_BUS_ADDRESS_SENSOR_COUNT:
response[0] = EGG_BUS_NUM_HOSTED_SENSORS;
response_length = 1;
break;
case EGG_BUS_ADDRESS_MODULE_ID:
memcpy(response, macaddr, 6);
response_length = 6;
break;
case EGG_BUS_FIRMWARE_VERSION:
big_endian_copy_uint32_to_buffer(EGG_BUS_FIRMWARE_VERSION_NUMBER, response);
break;
#ifdef INCLUDE_DEBUG_REGISTERS
case EGG_BUS_DEBUG_NO2_HEATER_VOLTAGE_PLUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_voltage(0), response);
break;
case EGG_BUS_DEBUG_NO2_HEATER_VOLTAGE_MINUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_feedback_voltage(0), response);
break;
case EGG_BUS_DEBUG_NO2_HEATER_POWER_MW:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_mw(0), response);
break;
case EGG_BUS_DEBUG_NO2_DIGIPOT_WIPER:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_wiper1(), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_VOLTAGE_PLUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_voltage(1), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_VOLTAGE_MINUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_feedback_voltage(1), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_POWER_MW:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_mw(1), response);
break;
case EGG_BUS_DEBUG_CO_DIGIPOT_WIPER:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_wiper0(), response);
break;
case EGG_BUS_DEBUG_DIGIPOT_STATUS:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_status(), response);
blinkLEDs(1, POWER_LED);
break;
#endif
default:
if(address >= EGG_BUS_SENSOR_BLOCK_BASE_ADDRESS){
sensor_index = sensor_block_relative_address / ((uint16_t) EGG_BUS_SENSOR_BLOCK_SIZE);
sensor_field_offset = sensor_block_relative_address % ((uint16_t) EGG_BUS_SENSOR_BLOCK_SIZE);
switch(sensor_field_offset){
case EGG_BUS_SENSOR_BLOCK_TYPE_OFFSET:
egg_bus_get_sensor_type(sensor_index, (char *) response);
response_length = 16;
break;
case EGG_BUS_SENSOR_BLOCK_UNITS_OFFSET:
egg_bus_get_sensor_units(sensor_index, (char *) response);
response_length = 16;
break;
case EGG_BUS_SENSOR_BLOCK_R0_OFFSET:
big_endian_copy_uint32_to_buffer(egg_bus_get_r0_ohms(sensor_index), response);
break;
case EGG_BUS_SENSOR_BLOCK_TABLE_X_SCALER_OFFSET:
memcpy(&responseValue, get_p_x_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_TABLE_Y_SCALER_OFFSET:
memcpy(&responseValue, get_p_y_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT_SCALER_OFFSET:
memcpy(&responseValue, get_p_independent_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT_OFFSET:
case EGG_BUS_SENSOR_BLOCK_RAW_VALUE_OFFSET:
possible_low_side_resistances[0] = get_r1(sensor_index) + get_r2(sensor_index) + get_r3(sensor_index);
possible_low_side_resistances[1] = get_r1(sensor_index) + get_r2(sensor_index);
possible_low_side_resistances[2] = get_r1(sensor_index);
// R2 and R3 enabled
SENSOR_R2_ENABLE(sensor_index);
SENSOR_R3_ENABLE(sensor_index);
_delay_ms(10);
possible_values[0] = averageADC(sensor_index);
// R3 disabled
SENSOR_R3_DISABLE(sensor_index);
_delay_ms(10);
possible_values[1] = averageADC(sensor_index);
// R2 and R3 disabled
SENSOR_R2_DISABLE(sensor_index);
_delay_ms(10);
possible_values[2] = averageADC(sensor_index);
// i'm going to abuse some variables to save space here
temp = ((1024L * get_sensor_vcc(sensor_index)) / ADC_VCC_TENTH_VOLTS) / 2L; //midrange_adc_value
responseValue = temp > possible_values[0] ? temp - possible_values[0] : possible_values[0] - temp; // responseValue = abs(adc_midpoint - adc[0])
if(min32(responseValue, temp > possible_values[1] ? temp - possible_values[1] : possible_values[1] - temp) == responseValue){
best_value_index = 0;
}
else{
best_value_index = 1;
responseValue = temp > possible_values[1] ? temp - possible_values[0] : possible_values[1] - temp; // responseValue = abs(adc_midpoint - adc[1])
}
// responseValue is the smaller difference to the midpoint between adc[0] and adc[1]
if(min32(responseValue, temp > possible_values[2] ? temp - possible_values[2] : possible_values[2] - temp) != responseValue){
best_value_index = 2;
}
if(sensor_field_offset == EGG_BUS_SENSOR_BLOCK_RAW_VALUE_OFFSET){
response_length = 20;
//the following returns the best value and the associated low side resistance
big_endian_copy_uint32_to_buffer((uint32_t) possible_values[best_value_index], response);
big_endian_copy_uint32_to_buffer((uint32_t) possible_low_side_resistances[best_value_index], response + 4 );
big_endian_copy_uint32_to_buffer((uint32_t) get_sensor_vcc(sensor_index), response + 8 );
big_endian_copy_uint32_to_buffer((uint32_t) ADC_VCC_TENTH_VOLTS, response + 12 );
big_endian_copy_uint32_to_buffer((uint32_t) 1024, response + 16 );
//the following returns the three ADC values and the algorithmic selection of the best one's index
//responseValue = ((uint32_t)possible_values[0]) << 16;
//responseValue |= possible_values[1];
//big_endian_copy_uint32_to_buffer(responseValue, response);
//responseValue = ((uint32_t)possible_values[2]) << 16;
//responseValue |= best_value_index;
//big_endian_copy_uint32_to_buffer(responseValue, response + 4);
}
// else{ // if sensor_field_offset == EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT
//
// if(possible_values[best_value_index] == 0){ // open circuit condition
// responseValue = 0xffffffff;
// }
// else if(best_value_index == 0 && possible_values[best_value_index] < get_sensor_min_adc_high_r(sensor_index)){ // resistance too large
// responseValue = 0xfffffffe;
// }
// else{
// // calculate the resistance
// // (sensor_vcc - sensor_v) * R_low / sensor_v = R_sensor
//
// responseValue = ADC_VCC_TENTH_VOLTS * possible_values[best_value_index];
// responseValue /= 1024L;
//
// // now responseValue is the sensor voltage in tenths of a volt
//
// temp = responseValue; // save sensor voltage for later
//
// responseValue = get_sensor_vcc(sensor_index) - temp;
//
// // now responseValue is the parenthetical numerator term
//
// responseValue *= possible_low_side_resistances[best_value_index];
//
// // now responseValue is the actual numerator
//
// responseValue /= temp;
//
// // now responseValue is the measured resistance
//
// temp = responseValue;
// responseValue *= get_independent_scaler_inverse(sensor_index);
// responseValue /= egg_bus_get_r0_ohms(sensor_index);
// }
//
// big_endian_copy_uint32_to_buffer(responseValue, response);
// }
break;
default: // assume its an access to the mapping table entries
sensor_block_relative_address = (sensor_field_offset - EGG_BUS_SENSOR_BLOCK_COMPUTED_VALUE_MAPPING_TABLE_BASE_OFFSET);
sensor_block_relative_address >>= 3; // divide by eight - now it is the mapping table index
response_length = 2;
*(response) = getTableValue(sensor_index, sensor_block_relative_address, 0);
*(response+1) = getTableValue(sensor_index, sensor_block_relative_address, 1);
break;
}
}
break;
}
// this gets called when you get an SLA+R
void onRequestService(void){
uint8_t response[EGG_BUS_MAX_RESPONSE_LENGTH] = { 0 };
uint8_t response_length = 4; // unless it gets overridden 4 is the default
uint8_t sensor_index = 0;
uint8_t sensor_field_offset = 0;
uint16_t address = egg_bus_get_read_address(); // get the address requested in the SLA+W
uint16_t sensor_block_relative_address = address - ((uint16_t) EGG_BUS_SENSOR_BLOCK_BASE_ADDRESS);
uint16_t possible_values[3] = {0,0,0};
uint32_t possible_low_side_resistances[3] = {0,0,0};
uint8_t best_value_index = 0;
uint32_t responseValue = 0;
uint32_t temp = 0;
switch(address){
case EGG_BUS_ADDRESS_SENSOR_COUNT:
response[0] = EGG_BUS_NUM_HOSTED_SENSORS;
response_length = 1;
break;
case EGG_BUS_ADDRESS_MODULE_ID:
memcpy(response, macaddr, 6);
response_length = 6;
break;
case EGG_BUS_FIRMWARE_VERSION:
big_endian_copy_uint32_to_buffer(EGG_BUS_FIRMWARE_VERSION_NUMBER, response);
break;
#ifdef INCLUDE_DEBUG_REGISTERS
case EGG_BUS_DEBUG_NO2_HEATER_VOLTAGE_PLUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_voltage(0), response);
break;
case EGG_BUS_DEBUG_NO2_HEATER_VOLTAGE_MINUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_feedback_voltage(0), response);
break;
case EGG_BUS_DEBUG_NO2_HEATER_POWER_MW:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_mw(0), response);
break;
case EGG_BUS_DEBUG_NO2_DIGIPOT_WIPER:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_wiper1(), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_VOLTAGE_PLUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_voltage(1), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_VOLTAGE_MINUS:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_feedback_voltage(1), response);
break;
case EGG_BUS_DEBUG_CO_HEATER_POWER_MW:
big_endian_copy_uint32_to_buffer(heater_control_get_heater_power_mw(1), response);
break;
case EGG_BUS_DEBUG_CO_DIGIPOT_WIPER:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_wiper0(), response);
break;
case EGG_BUS_DEBUG_DIGIPOT_STATUS:
big_endian_copy_uint32_to_buffer((uint32_t) digipot_read_status(), response);
blinkLEDs(1, POWER_LED);
break;
#endif
default:
if(address >= EGG_BUS_SENSOR_BLOCK_BASE_ADDRESS){
sensor_index = sensor_block_relative_address / ((uint16_t) EGG_BUS_SENSOR_BLOCK_SIZE);
sensor_field_offset = sensor_block_relative_address % ((uint16_t) EGG_BUS_SENSOR_BLOCK_SIZE);
switch(sensor_field_offset){
case EGG_BUS_SENSOR_BLOCK_TYPE_OFFSET:
egg_bus_get_sensor_type(sensor_index, (char *) response);
response_length = 16;
break;
case EGG_BUS_SENSOR_BLOCK_UNITS_OFFSET:
egg_bus_get_sensor_units(sensor_index, (char *) response);
response_length = 16;
break;
case EGG_BUS_SENSOR_BLOCK_R0_OFFSET:
big_endian_copy_uint32_to_buffer(egg_bus_get_r0_ohms(sensor_index), response);
break;
case EGG_BUS_SENSOR_BLOCK_TABLE_X_SCALER_OFFSET:
memcpy(&responseValue, get_p_x_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_TABLE_Y_SCALER_OFFSET:
memcpy(&responseValue, get_p_y_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT_SCALER_OFFSET:
memcpy(&responseValue, get_p_independent_scaler(sensor_index), 4);
big_endian_copy_uint32_to_buffer(responseValue, response);
break;
case EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT_OFFSET:
case EGG_BUS_SENSOR_BLOCK_RAW_VALUE_OFFSET:
possible_low_side_resistances[0] = get_r1(sensor_index) + get_r2(sensor_index) + get_r3(sensor_index);
possible_low_side_resistances[1] = get_r1(sensor_index) + get_r2(sensor_index);
possible_low_side_resistances[2] = get_r1(sensor_index);
// R2 and R3 enabled
SENSOR_R2_ENABLE(sensor_index);
SENSOR_R3_ENABLE(sensor_index);
_delay_ms(10);
possible_values[0] = averageADC(sensor_index);
// R3 disabled
SENSOR_R3_DISABLE(sensor_index);
_delay_ms(10);
possible_values[1] = averageADC(sensor_index);
// R2 and R3 disabled
SENSOR_R2_DISABLE(sensor_index);
_delay_ms(10);
possible_values[2] = averageADC(sensor_index);
// figure out the "best value index" ... here's how this algorithm works:
// If the ADC reading when using the R1 + R2 + R3 chain is below THRESHOLD1 use that value
// else if the ADC reading when using the R1 + R2 chain is below THRESHOLD2 use that value
// else use the ADC reading using the R1 chain
if(possible_values[0] < get_r1r2r3_threshold(sensor_index)){
best_value_index = 0;
}
else if(possible_values[1] < get_r1r2_threshold(sensor_index)){
best_value_index = 1;
}
else{
best_value_index = 2;
}
if(sensor_field_offset == EGG_BUS_SENSOR_BLOCK_RAW_VALUE_OFFSET){
response_length = 8;
big_endian_copy_uint32_to_buffer((uint32_t) possible_values[best_value_index], response);
big_endian_copy_uint32_to_buffer((uint32_t) possible_low_side_resistances[best_value_index], response + 4 );
}
else{ // if sensor_field_offset == EGG_BUS_SENSOR_BLOCK_MEASURED_INDEPENDENT
// in either case ... calculate the resistance
uint32_t a = ((uint32_t) possible_values[best_value_index]) * ADC_VCC_TENTH_VOLTS; // ADC_VCC * ADC
uint32_t b = (1024L * ((uint32_t) get_sensor_vcc(sensor_index))); // 1024 * SENSOR_VCC
if(a > b){
responseValue = 0; // short circuit
}
else{
// what we are computing is
// R_SENSOR = R_LOW_SIDE * SENSOR_VCC * (1024 * SENSOR_VCC - ADC_VCC * ADC) / (ADC_VCC * SENSOR_VCC * ADC)
// = R_LOW_SIDE * SENSOR_VCC * (b - a) / (ADC_VCC * SENSOR_VCC * ADC)
responseValue = b - a;
// before we multiply by a potentially large value lets find out if it's going to make us overflow and avert that if possible
if(possible_low_side_resistances[best_value_index] > (((uint32_t) 0xffffffff) / responseValue) ){
if(possible_values[best_value_index] != 0){
responseValue /= ((uint32_t) ADC_VCC_TENTH_VOLTS); // (b - a) / (ADC_VCC)
responseValue *= possible_low_side_resistances[best_value_index]; // R_LOW_SIDE * (b - a) / (ADC_VCC)
responseValue /= ((uint32_t) get_sensor_vcc(sensor_index) *
((uint32_t) possible_values[best_value_index])); // R_LOW_SIDE * (b - a) / (ADC_VCC * ADC * SENSOR_VCC)
responseValue *= get_sensor_vcc(sensor_index); // R_LOW_SIDE * SENSOR_VCC * (b - a) / (ADC_VCC * ADC * SENSOR_VCC)
}
else{
responseValue = 0xffffffff; // infinity
}
}
else{
responseValue *= possible_low_side_resistances[best_value_index]; // R_LOW_SIDE * (b - a)
if(possible_values[best_value_index] != 0){
responseValue /= ((uint32_t) possible_values[best_value_index]) *
((uint32_t) ADC_VCC_TENTH_VOLTS *
((uint32_t) get_sensor_vcc(sensor_index))); // R_LOW_SIDE * (b - a) / (ADC * ADC_VCC * SENSOR_VCC)
responseValue *= get_sensor_vcc(sensor_index); // R_LOW_SIDE * SENSOR_VCC * (b - a) / (ADC * ADC_VCC * SENSOR_VCC)
}
else{
responseValue = 0xffffffff; // infinity
}
}
}
// the independent variable in either case is R_Sensed / R0
//float_response = ((1.0 * responseValue) / egg_bus_get_r0_ohms(sensor_index));
temp = responseValue;
responseValue *= get_independent_scaler_inverse(sensor_index);
if(temp > responseValue){
// overflow the independent variable should be returned as big as possible
responseValue = 0xffffffff; // infinity
}
else{
responseValue /= egg_bus_get_r0_ohms(sensor_index);
}
big_endian_copy_uint32_to_buffer(responseValue, response);
}
break;
default: // assume its an access to the mapping table entries
sensor_block_relative_address = (sensor_field_offset - EGG_BUS_SENSOR_BLOCK_COMPUTED_VALUE_MAPPING_TABLE_BASE_OFFSET);
sensor_block_relative_address >>= 3; // divide by eight - now it is the mapping table index
response_length = 2;
*(response) = getTableValue(sensor_index, sensor_block_relative_address, 0);
*(response+1) = getTableValue(sensor_index, sensor_block_relative_address, 1);
break;
}
}
break;
}