Smart sensor code for KL05Z, including fixed ranging as well as auto-ranging.
Dependencies: mbed-src-KL05Z-smart-sensor
kl05z-smartsensor.cpp
- Committer:
- r14793
- Date:
- 2019-05-28
- Revision:
- 0:119db3edc934
File content as of revision 0:119db3edc934:
/**************************************************************************************** * * MIT License (https://spdx.org/licenses/MIT.html) * Copyright 2018 NXP * * MBED code for KL05Z-based "smart" current sensor, which measures current in * three ranges. Intended to be used with an aggregator board which triggers sensors * on all instrumented rails and then sequentially reads the data from each out over I2C. * * Because there is no crystal on the board, need to edit source mbed-dev library * to use internal oscillator with pound-define: * change to "#define CLOCK_SETUP 0" in file: * mbed-dev/targets/TARGET_Freescale/TARGET_KLXX/TARGET_KL05Z/device/system_MKL05Z4.c * ****************************************************************************************/ #include <mbed.h> static char version_info[] = {'S', 'O', 'S', 4, 22, 19}; // date info... (need to keep values to 8 bits or less...) // set things up... I2CSlave slave(PTB4, PTB3); // These will be used for identifying smart sensor build options: // voltage range (0-3.3V, 0-6.6V, and 12V), and // current range (high: 4A max, and low: 1.65A max) // (default pin pulls are pull up...) // But this still needs to be implemented per schematic... DigitalIn gpio0(PTA3); // R8 DigitalIn C_RANGE(PTA4); // R9 DigitalIn V_RANGE0(PTA5); // R10 DigitalIn V_RANGE1(PTA6); // R11 // configure pins for measurements... // analog inputs from sense amps and rail voltage (divider)... AnalogIn HIGH_ADC(PTB10); AnalogIn VRAIL_ADC(PTB11); AnalogIn LOW1_ADC(PTA9); AnalogIn LOW2_ADC(PTA8); // outputs which control switching FETs... DigitalOut VRAIL_MEAS(PTA7); // turns on Q7, connecting voltage divider DigitalOut LOW_ENABLE(PTB0); // turns on Q4, turning off Q1, enabling low measurement DigitalOut LOW1(PTB2); // turns on Q5, turning off Q2, disconnecting shunt R1 DigitalOut LOW2(PTB1); // turns on Q6, turning off Q3, disconnecting shunt R2 // set initial, default I2C listening address... // same one for all sensors so we don't need to individually program each one... int address = 0x48 << 1; // buffers for I2C communication char buf[15], inbuf[10]; char obuf[10], cbuf[10]; // another buf for compressed output... // variables... int i, j; bool waiting; bool big_data = false; // flag to save time during ISR // only process uncompressed data if explicitly called for... // these unions enable converting float val to bytes for transmission over I2C... union u_tag { char b[4]; float fval; int ival; } u, v; // define measurement result and status variables... float measurement1; float measurement2; char status=0; int n_meas=25; // number of averages when measuring... float vref =3.3; float factor_H = vref / 0.8; float factor_L1 = vref / (0.05 * 1000); float factor_L2 = vref / (2 * 1000); int wait_mbbb = 5; int wait_high = 250; int wait_low1 = 250; int wait_low2 = 500; int wait_vrail = 200; typedef enum { iAUTO, iHIGH, iLOW1, iLOW2, } i_range_t; i_range_t iRANGE = iAUTO; // flag for controlling auto/locked ranging for current measurement /*********************************************************************************** * * FUNCTIONS FOR MEASURING CURRENT AND VOLTAGE * ************************************************************************************/ void enableHighRange(){ LOW_ENABLE = 0; // short both low current shunts, close Q1 wait_us(wait_mbbb); // delay for FET to settle... (make before break) LOW1 = 0; LOW2 = 0; // connect both shunts to make lower series resistance VRAIL_MEAS = 0; // disconnect rail voltage divider wait_us(wait_high); // wait for rail settling... } void enableLow1Range(){ LOW1 = 0; LOW2 = 1; // disconnect LOW2 shunt so LOW1 can measure wait_us(wait_mbbb); // delay for FET to settle... (make before break) LOW_ENABLE = 1; // unshort low current shunts, open Q1 VRAIL_MEAS = 0; // disconnect rail voltage divider wait_us(wait_low1); // wait for rail settling... } void enableLow2Range(){ LOW1 = 1; LOW2 = 0; // disconnect LOW1 shunt so LOW2 can measure wait_us(wait_mbbb); // delay for FET to settle... (make before break) LOW_ENABLE = 1; // unshort low current shunts, open Q1 VRAIL_MEAS = 0; // disconnect rail voltage divider wait_us(wait_low2); // wait for rail settling... } void enableRailV(){ VRAIL_MEAS = 1; // turn on Q7, to enable R3-R4 voltage divider wait_us(wait_vrail);// wait for divider to settle... // Compensation cap can be used to make // voltage at ADC a "square wave" but it is // rail voltage and FET dependent. Cap will // need tuning if this wait time is to be // removed/reduced. // // So, as it turns out, this settling time and // compensation capacitance are voltage dependent // because of the depletion region changes in the // FET. Reminiscent of grad school and DLTS. // Gotta love device physics... } // when a divider is present, turn it off to remove the current it draws... void disableRailV(){ VRAIL_MEAS = 0; // turn off Q7, disabling R3-R4 voltage divider } // measure high range current... float measureHigh(){ float highI=0; enableHighRange(); for (i = 0; i < n_meas; i++){ highI += HIGH_ADC; } highI = factor_H * highI/n_meas; if (highI<0.000001) highI = 0; return highI; } // mesaure mid range current... float measureLow1(bool autorange){ float low1I=0; if (!autorange) enableLow1Range(); for (i = 0; i < n_meas; i++){ low1I += LOW1_ADC; } if (!autorange) enableHighRange(); low1I = factor_L1 * low1I/n_meas; if (low1I<0.000001) low1I = 0; return low1I; } // measure low range current... float measureLow2(bool autorange){ float low2I=0; if (!autorange) enableLow2Range(); for (i = 0; i < n_meas; i++){ low2I += LOW2_ADC; } if (!autorange) enableHighRange(); low2I = factor_L2 * low2I/n_meas; if (low2I<0.000001) low2I = 0; return low2I; } // this function measures current, autoranging as necessary // to get the best measurement... // hard coded values for switching ranges needs to be made // dynamic so 4.125A/1.65A ranges can be used... float measureAutoI(){ float tempI; enableHighRange(); // this should already be the case, but do it anyway... tempI = measureHigh(); status &= 0xF9; // if current is below this threshold, use LOW1 to measure... if (tempI < 0.060) { enableLow1Range(); tempI = measureLow1(false); // call function status &= 0xFA; // if current is below this threshold, use LOW2 to measure... if (tempI < 0.0009){ enableLow2Range(); // change FETs to enable LOW2 measurement... tempI = measureLow2(false); status &= 0xFB; } enableHighRange(); } if (tempI<0.000001) tempI = 0; // we cannot measure less than 1uA with stock population... return tempI; } // measure the rail voltage, default being with // need to add logic for 5V/12V/arbitraryV range... float measureRailV(){ float railv=0; enableRailV(); // switch FETs so divider is connected... for (i = 0; i < n_meas; i++){ railv += VRAIL_ADC; // read voltage at divider output... } disableRailV(); // now disconnect the voltage divider railv = vref * (railv/n_meas); // compute average // Convert to voltage by multiplying by "mult" if (vref==12.0) railv = railv * 0.24770642201; return railv; } /*********************************************************************************** * * INTERRUPT SERVICE ROUTINE * ************************************************************************************/ // measurements are only taken during ISR, triggered by aggregator on IRQ line... // this could have been implemented differently, but this was simple... // If coulomb counting is desired, this code would probably need to change... void interrupt_service(){ //(this is currently just a placeholder...) status &= 0xF8; // clear measurement status bits.. // make current measurement... switch (iRANGE){ case iAUTO: measurement1 = measureAutoI(); break; case iHIGH: enableHighRange(); measurement1 = measureHigh(); break; case iLOW1: enableLow1Range(); measurement1 = measureLow1(true); break; case iLOW2: enableLow2Range(); measurement1 = measureLow2(true); break; } // make voltage measurement... measurement2 = measureRailV(); // prepare data for transport, in the event that aggregator asks for short format... // compressed data format, 4 bytes total, with a status nibble // Each byte has form: (s*128) + (digit1*10) + (digit2), which fits into 8 bits // Each value is composed of two bytes with form above, first three digits are // the mantissa and the last digit is the exponent. Two values is four bytes, so // that allows four status bits to be included. sprintf(buf, "%4.2e", measurement1); buf[10] = (buf[0]-48)*10 + (buf[2]-48); // no decimal, we use fixed point... buf[11] = (buf[3]-48)*10 + (buf[7]-48); // no 'e', and no exp sign, since we know that's negative... sprintf(buf, "%4.2e", measurement2); buf[12] = (buf[0]-48)*10 + (buf[2]-48); // no decimal, we use fixed point... buf[13] = (buf[3]-48)*10 + (buf[7]-48); // no 'e', and no exp sign, since we know that's negative... // add in the four status bits... buf[10] = buf[10] | (status & 1<<3)<<4; buf[11] = buf[11] | (status & 1<<2)<<5; buf[12] = buf[12] | (status & 1<<1)<<6; buf[13] = buf[13] | (status & 1<<0)<<7; // Convert each 32-bit floating point measurement value into 4 bytes // using union, so we can send bytes over I2C... u.fval = measurement1; v.fval = measurement2; // now fill the buffers with the stuff generated above so it can be sent over I2C: // stuff latest measurement float values into bytes of buf for next transmission... // buffer format: 4 bytes = (float) V, 4 bytes = (float) I, 1 byte status for (j=0; j<4; j++) buf[j] = u.b[j]; // voltage for (j=0; j<4; j++) buf[j+4] = v.b[j]; // current buf[8] = status; // transfer compressed measurement data to output buffers... for (j=0; j<9; j++) obuf[j] = buf[j]; for (j=0; j<4; j++) cbuf[j] = buf[j+10]; } //ISR /*********************************************************************************** * * MAIN CODE * ************************************************************************************/ // main... int main() { buf[0] = version_info[0]; // force version info to be included in binary... buf[0] = 0; // turn on pull ups for option resistors, since resistors pull down pins C_RANGE.mode(PullUp); V_RANGE0.mode(PullUp); V_RANGE1.mode(PullUp); // change calculation multipliers according to option resistors: i = V_RANGE1*2 + V_RANGE0; if (i==1) vref = 6.6; if (i==2) vref = 12.0; if (C_RANGE==0) { factor_H = vref / 2.0; factor_L1 = vref / (0.15 * 1000); factor_L2 = vref / (15 * 1000); } status |= C_RANGE<<6 | V_RANGE1<<5 | V_RANGE0<<4; // add option resistors into full status... wait_us(200); // delay before reassigning SWD pin so as to not get locked out... DigitalIn my_select(PTA2); // this is the individual line to each sensor... while (my_select) { // wait forever here until aggregator signals us for address reassignment... } // end while // Need to delay set up of I2C until after we've come out of wait loop above // -- because -- // Setting up the I2C earlier starts it listening on the bus even if it's not // being polled, which means that multiple sensors will respond, hanging the bus... slave.frequency(400000); // go as fast as possible... slave.address(address); // listen on the default address... while (!my_select) { // listen for new address, then repeat it back aggregator... waiting = true; while (waiting && !my_select){ int i = slave.receive(); switch (i) { case I2CSlave::WriteAddressed: slave.read(buf, 1); // we just got our new address, provided my_select subsequently changes... waiting = false; break; case I2CSlave::ReadAddressed: slave.write(buf, 1); // write back our new address to confirm we go it... waiting = false; break; } } } // end while, waiting for address reassignment... // we fell out of loop above, so now change our I2C address to the newly assigned one... // this newly assigned address will not change until we're reset... slave.address(buf[0]); // enable interrupts, need to wait until after getting our new I2C address, // since we cannot respond until we have our new address... InterruptIn triggerIRQ(PTA0); // this is the ganged interrupt signal to all sensors triggerIRQ.rise(&interrupt_service); // attach the service routine... // make sure we can receive at the new address... // this isn't absolutely necessary, but it's a good check... // if this is removed, the corresponding write in the aggregator code needs to go, too // **** maybe we should change this to reading back the status option resistors... *** waiting = true; while (waiting){ i = slave.receive(); switch (i) { case I2CSlave::ReadAddressed: slave.write(buf, 1); waiting = false; break; case I2CSlave::WriteAddressed: slave.read(buf, 1); waiting = false; break; } } /******************************************************************************/ // this is the main loop: // We just sit here and wait for I2C commands and triggers on IRQ line... // // A triggerIRQ causes measurements in ISR, aggregator must wait at least // long enough for it to finish before reading back the result(s). // // results are sent in 9 byte packets: 4 for voltage, 4 for current, and one status, // where voltage and current are floats in units of V and A. Status byte will be // packed with something later, yet to be defined. // // What should be implemented are additional things like setting and reading // back the delays in the GPIO control functions, turning on and off averaging // so we can see what the min and max values are (which also helps tell if we // don't have enough delay in the GPIO functions), and possibly other stuff // not thought of yet... Definitely not an exercise for this pasta programmer... // while (1) { i = slave.receive(); switch (i) { case I2CSlave::ReadAddressed: if (my_select){ // if high, send uncompressed format... slave.write(obuf, 9); waiting = false; } else { // if low, send compressed format... slave.write(cbuf, 4); waiting = false; } break; case I2CSlave::WriteAddressed: if (!my_select){ // if low, receive one byte... slave.read(inbuf, 1); waiting = false; } else { ;// if high, receive two bytes... slave.read(inbuf, 2); waiting = false; // if we're here, we've recieved two words, so we update the // appropriate parameter. switch (inbuf[0]) { case 0: wait_mbbb = inbuf[1]; break; case 1: wait_high = inbuf[1]*8; break; case 2: wait_low1 = inbuf[1]*8; break; case 3: wait_low2 = inbuf[1]*8; break; case 4: wait_vrail = inbuf[1]*8; break; case 5: n_meas = inbuf[1]; break; case 127: // range select command, and pre-fill obuf param for range ([8]) switch (inbuf[1]) { case 0: iRANGE = iAUTO; obuf[8] = 0; break; case 1: iRANGE = iHIGH; obuf[8] = 1; break; case 2: iRANGE = iLOW1; obuf[8] = 2; break; case 3: iRANGE = iLOW2; obuf[8] = 3; break; } break; } // switch // and since we're still here, place the new values // in obuf so we can read back all paramters values obuf[0] = wait_mbbb; obuf[1] = wait_high/8; obuf[2] = wait_low1/8; obuf[3] = wait_low2/8; obuf[4] = wait_vrail/8; obuf[5] = n_meas; obuf[6] = 0; obuf[7] = 0; //obuf[8] = 0; } } // switch } // while(1) }