I was curiuos to find out how fast the interrupt response of a STM32H743 can be. I connected a simple square wave generator to Pin PG3 of my old NUCLEOH743ZI-Board. A PWM output of my raspberry Pi PICO was used as a square wave generator Read More …
Schlagwort: STM32H7
How to connect an ADC3660 to an MCU (part II)
The following timing diagram (that I draw with Wavedrom, a fantastic tool for that purpose) shows in the upper part the output format of the ADC3660 as I understand it from the datasheet: The signal in the middle („NSS_TI“) shows the NSS signal as it Read More …
How to connect an ADC3660 to an MCU (part I)
TI’s new family of SAR-ADCs with integrated DDCs could be a game changer for building SDRs for HAM radio operators. Why? Because these ADCs do not only contain an NCO and a complex digital IQ downmixer, they also integrate a decimation stage and an output Read More …
SI5351A and frequency counting with the STM32H743
I wanted to play around with the SI5351A clock generator, but for verifying the output frequencies of the SI5351 I thought it would be great to have a frequency counter at hand. Unfortunately I do not own a frequency counter, so I looked for some Read More …
H7 ADC revisited (Bandpass sampling and analog bandwidth of the 16-bit ADC peripheral of the STM32H7, Part IV)
The question that interested me was: How strongly does the SNR of the ADC-peripheral of the H7 depend on the chosen clock source? Unfortunately, neither the H7 datasheets nor application notes like AN5354 treat this topic. The FFT plot shown in figure 1 of AN5354 Read More …
H7 ADC revisited (Bandpass sampling and analog bandwidth of the 16-bit ADC peripheral of the STM32H7, Part III)
Summary: It is shown that the shape of the transfer function and of the SNR of the internal ADC of the STM32H7 vs. frequency of the applied signal can be explained with a very simple simulation model up to quite high signal frequencies. The PLL Read More …
Improved Reception of Radio DARC; preamp unnecessary
CIC compensation filters now follow the 2-stage decimating CIC filters for the I-Q-signals. The CIC compensation filters are two identical FIR filters (one filter each for the I signal and an identical filter for the Q signal) with currently 81 taps. They flatten the passbands Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part III)
continued from part II: The passband of CIC filters is not flat. This begs the question of whether this behavior should be corrected. In most cases, the CIC is therefore followed by a so-called CIC compensation filter. Zooming into the filter plot of the sinc4/dec.15 Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part II)
continued from part I: As explained in part I, the first version of my H7-SDR uses only one CIC filter of the DSFDM for filtering the I-signal and another one for filtering the Q-signal. However, the DSFDM contains 4 filters (see chapter 30 of RM0433 Read More …
The DFSDM of the STM32H7 or 128 != 16×8 != 8×16 (Part I)
My software defined radio for receiving AM transmissions in the 49 m band (see https://dm1cr.de/reception-of-radio-darc-transmission-with-a-microcontroller-only-sdr) looks quite primitive in the first version: It comprises a bandpass filter for anti-aliasing, an STM32H743ZI microcontroller and an audio amplifier with loudspeaker. The ADC inside of the STM32H7 is Read More …