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About Hoerz
since
04-06-2022
01-09-2023
Hoerz
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01-09-2023
04:11 PM
Hello BSTRobin! Thank you for trying to reproduce the problem. I am currently wondering why you receive data ready interrupts before the initialization has been completed. At which point of time do you write to register (0x58) INT_MAP_DATA? Why is there such a long delay (more than 20ms) between writing to register 0x58 and init complete? Thank you very much in advance! Julian
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12-14-2022
01:25 PM
Hello all! I have a question (or a challenge) regarding the data ready interrupt of the BMA456. My wish would be quite simple, to read out the unfiltered acceleration sensor values every 2,5ms. Therefore I operate the sensor with 400Hz and configure the sensor with ACC_Conf.acc_perf_mode = 1 and ACC_Conf.acc_bwp = 0x02 (normal mode) I observed that about 4 samples are missed after configuration before the first data-ready interrupt occurs. In other words: I'd expect the data ready interrupt about 2,5ms after configuration but actually the data ready interrupt is triggered 12ms after configuration. All interrupts after the first interrupt come with a frequency of 400Hz. See following image: If I change the configuration to ACC_Conf.acc_perf_mode = 0 and ACC_Conf.acc_bwp = 0x00 the sensor delivers the data as expected, see following image. How does the sensor behave when ACC_Conf.acc_perf_mode = 0 and PWR_CONF.adv_powersave = 0 are set at the same time? Unfortunately, this configuration is not described in chapter 4.3 of the BMA456 datasheet. I thought that the following configuration would be correct for this: ACC_Conf.acc_perf_mode = 1 ACC_Conf.acc_bwp = 0x02 -> designated as "normal mode" But this configuration does not work as expected (as shown above). My key questions are: - How does the sensor behave when ACC_Conf.acc_perf_mode = 0 and PWR_CONF.adv_powersave = 0 are set at the same time? - Why are approx. 4 samples missing when I use the configuration ACC_Conf.acc_perf_mode = 1 and ACC_Conf.acc_bwp = 0x02 (normal mode)?
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04-14-2022
11:53 AM
Hi BSTRobin, you summarized exactly the problem which we would like to solve. With the help of a Sensortec colleague we found a "workaround". We are cross-checking another register (pair), e.g. register 0x0F and 0x10. Those registers are both non-zero for BMA253 and all zeros for BMA456. 1. Send read command for register 0x0F (8 SPI Clock cycles) 2. Keep the SPI clock ON for additional 16 SPI Clock cycles and store the last received byte -> If the last received byte is non-zero -> BMA253 (actual received register 0x10) -> If the last received byte is zero -> BMA456 (actual received register 0x0F) Regarding your second point @BSTRobin wrote: In addition, pin 11 of BMA253 is the pin that determines whether to use SPI or I2C interface, which needs to be connected to GND. We are connecting pin 11 to GND for both BMA253 and BMA456 and that is allowed in the datasheets.
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04-07-2022
09:47 AM
@SterlingMinsha wrote: Hello, I've read an article about ensuring that there is no misidentification of the sensor before. I wonder if it helps you? Hi SterlingMinsha! Thanks for your reply. Unfortunately this has nothing to do with my decribed problem.
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04-06-2022
03:09 PM
Hello all! I have a question (or a challenge) regarding the automatic detection of the sensors BMA253 and BMA456. My situation: I am working for Bosch (other division, not senortec) and we are currently using the BMA253 sensor on our hardware. Now we would like to shift to the new sensor BMA456. In order to simplify the manufacturing process we would like to implement an automatic software-based detection of the mounted sensor. In theory we could simply readout the chip ID but that is exactly the crucial problem: Problem 1: The SPI communication if different for the sensors BMA253 and BMA456. For the BMA253 the read-response starts after 8 SPI clock cycles, see following image: For the BMA456 the read-response starts after 16 SPI clock cycles, see following image: In order to perform an automatic detection I would have to read two bytes and in one of them should be a correct chip ID. But in theory it is also possible to have two correct chip IDs in both bytes. Problem 2: The BMA456 starts sending after 8 SPI clock cycles dummy values. I measured those values and they change often. I could not verify that those values will never correspond to the chip ID of the BMA253. The BMA253 starts sending after 8 SPI clock cycles its correct Chip ID but after 16 it sends the values of register 0x01. This is a reserved register and I could not verify that those values in register 0x01 will never correspond to the chip ID of the BMA456. In most of the cases that sensors would be detected correctly but there might be some cases where two correct Chip IDs are read. We want to use this software in million products and we have to make sure that there is no misidentification of the sensor. Questions: - Is it possible for the BMA253 that the register 0x01 contains the Chip ID of the BMA456? -> If yes: Is it possible that this register will not change its content if it is read out multiple times? - Is it possible for the BMA456 that the dummy values correspond to the Chip ID of the BMA253? -> If yes: Is it possible that these dummy values will not change if read out multiple times? - Do you have any other ideas how a automatic software-based detection could be done? Thank you very much for your answers in advance! Julian
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