2020-01-30 07:47 AM
I have a system containing a LSM9DS1 sampling AXL and Mag at 50Hz (gyro is disabled). When the LSM9DS1 is not attached (desoldered) our system (MCU only) draws about 2mA (10mV average over a 5 ohm resistor). This is constant and stable current of 2mA i.e. almost a flat line.
When the LSM9DS1 is attached power consumption increases as expected, however;
1 - From graph below min current increases from about 2mA to about 2.5mA (0.5mA increase)
2 - However sometimes the system now pulls about 4.4mA at freq of 160Hz (increase of 2.4mA)
3 - Sometimes system pulls 7mA (increase of 5mA).
This results in the wild plot you see below. Any obvious reasons for this sort of current waveform? I have tried changing lots of LSM9DS1 settings with no improvement. I am under the impression it should draw about 600uA with gyro disabled.
Here are my config settings;
configureAXL(0x10,0x00); //CTRL_REG1_G (10h) //gyro off
configureAXL(0x11,0x00); //CTRL_REG2_G (11h)
configureAXL(0x12,0x00); //CTRL_REG3_G (12h)
configureAXL(0x13,0x00); //ORIENT_CFG_G (13h)
configureAXL(0x1E,0x00); //CTRL_REG4 (1Eh) 0011 1000
configureAXL(0x1F,0x38); //CTRL_REG5_XL (1Fh) 0011 1000
configureAXL(0x20,0x50); //CTRL_REG6_XL (20h) 0x70 = 119Hz, 0x50 = 50Hz
configureAXL(0x21,0x00); //CTRL_REG7_XL (21h)
configureAXL(0x22,0x04); //CTRL_REG8 (22h) 0000 1100
configureAXL(0x23,0x04); //CTRL_REG9 (23h) 0000 0100
configureAXL(0x24,0x00); //CTRL_REG10 (24h) 0100 0000
configureAXL(0x2E,0x00); //FIFO_CTRL (2Eh)
configureMAG(0x20,0xFC); //CTRL_REG1_M (20h) 1111 1100 - 80Hz
configureMAG(0x21,0x20); //CTRL_REG2_M (21h) 0010 0000 +/- 8 gauss
configureMAG(0x22,0x80); //CTRL_REG3_M (22h) 1000 0100 was 0x00
configureMAG(0x23,0x0C); //CTRL_REG4_M (23h) 0000 1100
configureMAG(0x24,0x00); //CTRL_REG5_M (24h) 0000 0000
configureMAG(0x30,0x00); //INT_CFG_M (30h) (need to set to 0x00)
configureMAG(0x31,0x00);
configureMAG(0x32,0x00); //INT_THS_L(32h)
configureMAG(0x33,0x00); //INT_THS_H(33h)
Any help appretiated.
Thanks
(Graph time is in mS)
2020-02-01 01:19 AM
The mag sensor was in ultra performance mode at 80Hz, which is the cause of those high current readings. With the mag sensor on medium performance and a lower ODR, the current draw is a lot less as described in the datasheet.
It would be good if the datasheet as some more current values noted at difference performance settings, there is little information about this.