BHA250B

Product FAQ

This is a product specific FAQ for smart sensors

Questions	Answers
Questions Q1: When the BHy is in suspend mode, are its GPIOx pins powered? If a GPIO pin is programed to output high, will the pin output be high even when BHI160 is in suspend mode (with all sensors are disabled)?	Answers Yes. As tested, when GPIO1, 2, 3 were set to output high, the GPIOs output kept high during all sensors were both enabled and disabled. So the GPIO pins can hold high when all sensors are disabled.
Questions Q2: Why does the current consumption of BHy samples seem higher than normal? For example, when GPIO1, 2, 3 are set to high output, ~280uA current is consumed even when no sensor is enabled.	Answers This leakage current is probably induced by the PD resistors when the GPIO pins are set to output high. Actually, there are two places that users can configure the PUPD states of a GPIO: one is in the ‘.cfg’ file code, and another is in the RAM patch code. So please check both and make sure the PD/PU (or both) resistors are disabled when you want to set the GPIO output high, low or toggling.
Questions Q3: Could you explain how to configure the GPIO in the cfg file? Below example shows a configure section of a .cfg file. The line with blue color is the place for GPIO configuration.	Answers Below example shows a configure section of a .cfg file. The line with blue color is the place for GPIO configuration. #Global Configuration irq,6 pull,down,down,down,down,down,down,down,none noexec,0 upload-speed,400 fifo,50.00 For example, if you want to enable GPIO1 PD and GPIO2 PU with all others disabled, you can modify that line to below: modified line(enable GPIO PD, GPIO2 PU, all other GPIOS’ disabled, ‘pull’ is the keyword) pull,none,down,up,none none,none,none,none
Questions Q4: Is the physical sensor status of ACC is power down when HW step counter is enabled? Why?	Answers Yes. Some physical sensors can be powered separately from ACC sensor in driver, such as HW step counter. So when such sensor is enabled, the physical ACC sensor remains power down. This function is used for debugging purpose.
Questions Q5: What is the speed range of I2C the BHy sensors can support?	Answers 100KHz, 400KHz, 1MHz I2C speed are supported and were tested on U7183-sensor I2C bus.
Questions Q6: I got a waveform form customer HW team about BHA250. There was a drop pulse on SDA after powering up, which was coming from other device on the I2C bus. Does this drop pulse on SDA influence the normal operation of BHy?	Answers No, because the pulse width is ~2us, which is large enough for the BHy I2C controller to detect a START condition and then a STOP condition. So after the detection of STOP condition, the BHy considers the I2C bus is released and return back to IDLE and normal status. More information
Questions Q7: When testing the current of a BHy mounted on shuttle board connecting to APP2.0 board platform, why is the current figure is higher than expected data released by V&V team & PM?	Answers This is because the BHy was running under different conditions. First, In V&V tests, the test setup was based on CLCC phones, in which the BHy (MCU + BMI / BMA) is working at 1.8V and the AP acts as a host of BHy. Moreover, V&V team normally tests the current of U7183 (MCU) and sensor(s) (BMI or BMA or Mag sensor) separately. Below table is an example of the current test results released by V&V team. Please note that the current is similar when tests with BHy sample (compared to U7183 + BMI / BMA): Table Note1: Use FASTEST ODR = 200Hz when applicable; for some virtual sensors Output Date Rate(ODR) is not applicable, i.e. step counter, significant motion sensor, AR, Tilt, etc. Second, there are some differences between CLCC phone tests and APP2.0 board + BHY shuttle: 1. The APP board by default enables the internal pull-down resistors (~100Kohms) on all MultIO pins. This draws some leakage current from INT pin of BHy when INT is output High. The leakage current is around 33uA (3.3V / 100Kohm). Therefore, the idle current (after powering up) of BHy shuttle is around 42uA, including 8uA from BHy sample itself. 2. The APP2.0 board has fixed 3.3V power supply, while it is 1.8V in CLCC phone. The higher voltage level causes higher current consumption. 3. Please switch off all other Mag sensors on shuttle board and reserve the only one you want, or switch off all Mag sensors to avoid unexpected current leakage during tests. Current consumption test on BHI160 sample Test setup: APP2.0 board + BHI160 shuttle board + DD2.0(UI) or APP1.0 board + BHI160 shuttle board + Python scripts Table Current consumption over different voltage of BHI160 Test setup: APP1.0 board + BHI160 shuttle board + Python scripts Table

Questions	Answers
Questions Q1: BHA250 has 3 GPIO pins. All of these GPIOs can be detected interrupt from secondary interfaced sensor, is this correct?	Answers For BHA250, there are GPIOs below: RSV1(GPIO0) dedicated for INT1_bma2x2 GPIO1 shared with INT2_bma2x2, output LOW during powering up until downloading patch. Be careful to connect external sensor GPIO2 can be freely used, can be configure as input/output/interrupt GPIO6(INT) dedicated for INT to host, not recommend for other usage SA_GPIO7 share with SA0(I2C address selection), better short to GND From the list above, only 2 GPIOs(GPIO1, GPIO2) can be used as external interrupt; And for GPIO1, we should check further the default status of the INT pin of connected external sensor.
Questions Q2: How do you configure BHA250 interrupt setting? Is there a document for this? For example, how to set which GPIO pin, how to set detect method (edge or level), how to set default level (active high or low).	Answers We can specify GPIO pin in board configuration file. #Physical Drivers #DriverID,Addr,GPIO,Cal0,Cal1,Cal2,Cal3,Cal4,Cal5,Cal6,Cal7,Cal8,Off0,Off1,Off2,Range m11,16,-, 0,-1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0 a48,105,0, 1, 0, 0, 0,-1, 0, 0, 0,-1, 0, 0, 0, 0 g49,105,-, 1, 0, 0, 0,-1, 0, 0, 0,-1, 0, 0, 0, 0 Please find the GPIO configuration in red. One special case is “-“. We specify “-“ when no interrupt is needed by this physical driver. Currently the only supported interrupt mode is rising edge (Active high) for secondary sensors.
Questions Q3: What are the possible side effects if watermark if NON-WAKEUP FIFO is set to very high level, say >90%?	Answers Fuser core transfers the wakeup FIFO before the non-wakeup FIFO. When the watermark is very large, the non-wakeup FIFO can overflow even if the wakeup FIFO did not (since data is still accumulating in both FIFOs during the transfer). If the non-wakeup FIFO overflow meta event is enabled, fuser core clears the count of discarded bytes as soon as it places the overflow meta event in the FIFO. In this case, everything works as expected. But, if the non-wakeup FIFO overflow meta event is disabled, Fuser core does not clear the count of discarded bytes until host transfer ends. Fuser core clears it later, after checking to see if watermarks is passed again. Here is a limitation in current design: if the discarded bytes count is non-zero, even if the watermark is not exceeded, fuser core assumes (incorrectly) that overflow must have happened. Because of this, we may be able to see following FIFO data output example, which is accepted for GEN1. The solution is to simply enable non-wakeup FIFO overflow meta event. <6>[ 6282.760293] [D]<7>BHI <631>irq_work_func entry, timestamp: 1421139992586049 <6>[ 6282.761138] [D]<7>BHI <540>Fifo length: 21908 <6>[ 6283.297812] [D]<7>BHI <631>irq_work_func entry, timestamp: 1421139993112048 <6>[ 6283.298304] [D]<7>BHI <540>Fifo length: 2727 <6>[ 6287.220066] [D]<7>BHI <631>irq_work_func entry, timestamp: 1421139997045774 <6>[ 6287.221365] [D]<7>BHI <540>Fifo length: 21908 <6>[ 6287.758927] [D]<7>BHI <631>irq_work_func entry, timestamp: 1421139997570398 <6>[ 6287.759426] [D]<7>BHI <540>Fifo length: 2727
Questions Q4: How to swab the FW content during FW download	Answers Table
Questions Q5: How Axis remapping is done for BHy?	Answers There are several ways to adjust axis mapping: Change setting in board config file and then re-compile; Reconfigure ELF file; Modify axis mapping at run-time. Axis remapping data is called as “Orientation Matrix” inside of fuser core, and is stored as part of “Physical Sensor Information”. The calibration matrix is output in the same order as the elements are listed in the board .cfg file used to generate a firmware image, described in the U7183 Application Note 007 Programming Guide section 6.4, where each matrix element is stored in successive nibbles. For example, if the board .cfg file contains: #DriverID,Addr,GPIO,C0,C1,C2,C3,C4,C5,C6,C7,C8,Off0,Off1,Off2,Range a9, 24, 3, 1, 0, 0, 0, -1, 0, 0, 0, -1, 0, 0, 0, 0 Or, if the stuffelf utility were used to generate the .fw file using the command line: stuffelf outerloop.elf –a -d24 -p3 -c1,0,0,0,-1,0,0,0,-1 Then bytes 11-15 of the Physical Sensor Information structure would be: Byte 11: 01 (hexadecimal) Byte 12: 00 Byte 13: 0F Byte 14: 00 Byte 15:0F The matrix is used to correct the orientation of physical sensor axes to match the required ENU (east north up) orientation required by Android. The calculation is performed as: Please click here for details Please click here for details Reference code is uploaded https://inside-ilm.bosch.com/irj/go/nui/sid/20055aba-64bf-3310-c480-9ee589d6e59b
Questions Q6: How to interpret BHy FIFO? Is there an example?	Answers Here is a sample FIFO data: FC C1 40 01 51 01 CC 0C F3 1C 00 0B 69 09 A6 F7 77 DB 04 33 22 02 14 60 14 38 F7 BC DF 9E 32 88 08 03 52 19 FA F7 D2 00 03 We can devide the FIFO data into the following frames: Table
Questions Q7: What is the recommended I2C bandwidth between BHy and AP?	Answers The recommended I2C bandwidth is 800K. In case I2C bandwidth is lower (say, 400K), I2C may be the blocker in data transfer between BHy and AP, in case some 200hz virtual sensors are running and BSX_A/B/C raw data are enabled in the background as well. The phenomenon could be unsmooth virtual sensor outputs in SensorList or 3DCompass or PhotoSafari, etc.
Questions Q8: Why is the Accel virtual sensor enabled by default in some cases	Answers Most probably the virtual sensor is enabled by Android Location service. The setting must be modified to disable it.
Questions Q9: Compilation is broken after make clean, how can this be fixed?	Answers Full SDK supports make clean, but the Customer SDK does not. Make clean will delete object that are necessary for the linking process. Please start from a new fresh SDK and copy over your changes.
Questions Q10: “ERROR: no driver in firmware” after changing the driver ID, what to do?	Answers There may still be a compiled version with the old driver ID. Delete the /sym and /obj folders when changing the driver ID in the driver.config file.
Questions Q11: What is the size limit for a sensor event data in the FIFO? In host interface the maximum size is 17 for BSX_A/B/C virtual sensors.	Answers The maximum size is 17 bytes, and it is a hard limit.
Questions Q12: How to move global variables from data RAM(16KBytes) to code RAM(32KBytes)?	Answers Unsigned char __attribute__ ((section (".rodata"))) test[3*1024];