@@ -10,6 +10,8 @@ ST micros require an ST-Link for programming and debugging, which is a dedicated
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@@ -10,6 +10,8 @@ ST micros require an ST-Link for programming and debugging, which is a dedicated
And lastly [here's the actual frequency response of the LC circuit changing as a large chunk of aluminum is brought over the coil](./images/frequency_response.mp4) It's hard to make out, but it's varying between 1.4 and 1.6 MHz, where frequency increases with the presence of aluminum. Steel had a similar, but slightly less prominent response (although the two pieces of metal were very different sizes so don't read into that too much). The steel target also reduced the amplitude of the response, and yielded cleaner, presumably less noisy oscilations.
And lastly [here's the actual frequency response of the LC circuit changing as a large chunk of aluminum is brought over the coil](./images/frequency_response.mp4) It's hard to make out, but it's varying between 1.4 and 1.6 MHz, where frequency increases with the presence of aluminum. Steel had a similar, but slightly less prominent response (although the two pieces of metal were very different sizes so don't read into that too much). The steel target also reduced the amplitude of the response, and yielded cleaner, presumably less noisy oscilations.
For next week, here's a nice blog post I found about [speeding up HAL's SPI transactions.](https://keepdevelopingprojects.wordpress.com/2020/09/09/reducing-stm32-spi-hal-latency/) One good reason to prefer ST to Atmel/Microchip here is that CubeMX generates MCU-specific initialization code, and actually going in to speed things up involves appreciably less searching for registers in datasheets.
## HTMSTMAA Week 7 - 4/15/21
## HTMSTMAA Week 7 - 4/15/21
This week I switched gears from working on the dynamometer and set out to start communicating with the [LDC1101](https://www.ti.com/product/LDC1101) from TI. The LDC1101 is an inductive to digital converter that uses an external [LC tank circuit](https://en.wikipedia.org/wiki/LC_circuit) to measure changes in impedance (Rp measurement mode) or resonant frequency (LHC mode) of the oscillator, relative to the change in presence of conductive or magnetically permeable materials respectively. Despite the existence of plenty of inductive to digital converters on the market (many of which are 2 or 4 channel devices in a single package), the LDC1101 is the only one I could find that uses SPI, and has a sample rate fast enough for high speed rotary encoding. These encoders are a bit of a bear to configure, and require multiple spreadsheets and a pretty thorough read through the datasheet. With that said, there aren't many other sensing options that provide 24 bits with noise this low, and with SPS + communication this fast.
This week I switched gears from working on the dynamometer and set out to start communicating with the [LDC1101](https://www.ti.com/product/LDC1101) from TI. The LDC1101 is an inductive to digital converter that uses an external [LC tank circuit](https://en.wikipedia.org/wiki/LC_circuit) to measure changes in impedance (Rp measurement mode) or resonant frequency (LHC mode) of the oscillator, relative to the change in presence of conductive or magnetically permeable materials respectively. Despite the existence of plenty of inductive to digital converters on the market (many of which are 2 or 4 channel devices in a single package), the LDC1101 is the only one I could find that uses SPI, and has a sample rate fast enough for high speed rotary encoding. These encoders are a bit of a bear to configure, and require multiple spreadsheets and a pretty thorough read through the datasheet. With that said, there aren't many other sensing options that provide 24 bits with noise this low, and with SPS + communication this fast.
