I have to do a project for my Uni, where one of the requirements is to connect DAC (AD5721 - Datasheet) with STM32F405RGT6 (Datasheet - package : LQFP64). My project so far

This is what I have so far (DAC connected with REF02) and now I have a problem how should I connect STM with DAC. The only thing I found is that STM has pins PA4 and PA5 that can be used as DAC_OUT and I'm stuck since then.

Next thing I'm supposed to do after this is to connect JTAG(IDC20) and RS232 to STM. I haven't tried anything with it yet since I need to solve previous problem first but if it's not a trouble I would also like to get some tips about this stuff too.

  • \$\begingroup\$ The chip uses serial interface, search for SPI. \$\endgroup\$
    – Long Pham
    Jun 9, 2018 at 15:43
  • \$\begingroup\$ The STM32F4 has 2 DAC outputs built-in. Why using an external one? \$\endgroup\$
    – user115094
    Jun 9, 2018 at 16:14
  • \$\begingroup\$ Unfortunately that's one of the requirements for some reason. \$\endgroup\$
    – SecondEnd
    Jun 9, 2018 at 16:40

1 Answer 1


From the data sheet of DAC:

Data is written to the AD5761/ AD5721 in a 24 -bit word format via a 4 -wire digital interfac e that is serial peripheral interface (SPI ) compatible . The devices also offer an SDO pin to facilitate daisy -chaining and readback.

One would need to connect SPIx_MOSI, SPIx_MISO, SPIx_NSS (chip select) and SPIx_SCK. depending on other functional requirements any of the multiple SPI modules present in MCU can be chosen.

Word of caution i see that the DAC is 5 V device but logical communication (SPI) voltage can be set to variable voltage. Since, the MCU can be operated only upto 3.3 V, please set the value of DVCC of DAC pin to same as VDD pin of MCU. Both should have same supply voltage level.

JTAG is pretty easy and straight forward:

New debug connectors for ARM

ALso, refer to the Nucleo boards from ST for some connections (JTAG, especially) you will get a fair idea. It also helps in other interfaces. Read the datasheet too for the features and alternate functions supported.

  • \$\begingroup\$ SPI_NSS is not strictly needed, one can use any GPIO under software control to do the chip select (and for some slaves the NSS pin under hardware control will not work, but it can be switched to GPIO of course) \$\endgroup\$
    – Arsenal
    Jun 9, 2018 at 21:33
  • \$\begingroup\$ @arsenal I totally agree with the latter part. Switching the NSS to GPIO part in case. \$\endgroup\$
    – User323693
    Jun 10, 2018 at 4:47

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