# External DAC

**URL:** <https://discourse.myriadrf.org/t/external-dac/2820>\
**Category:** LimeSDR\
**Created:** [16 May 2018 12:57 UTC](https://discourse.myriadrf.org/t/external-dac/2820 "2018-05-16T12:57:22Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [16 May 2018 16:27 UTC](https://discourse.myriadrf.org/t/external-dac/2820/2 "2018-05-16T16:27:09Z")

</div>

I’m guessing you’d need to modify the FPGA gateware. Something similar-ish was done for the larger LimeSDR-USB board — albeit to give SPI access to the LMS7002M from a micrcontroller attached via GPIO.

> [@Control LimeSDR via SPI using Arduino MCU](https://discourse.myriadrf.org/t/control-limesdr-via-spi-using-arduino-mcu/981/18):
>
> Well, FPGAs are a different paradigm. In an FPGA you are literally fabricating logic to run bits around your board at the hardware level. This allows, for example, having instantaneous and asynchronous, non-clocked propagation of logic signals (concurrent logic); likewise, you can also build state machines running synchronously on some clock domain you define. FPGAs are the closest thing to the highest speed you can get, other than building a custom application specific IC (ASIC). VHDL (als…

@Zack could likely advise.

---

_[View the full topic](https://discourse.myriadrf.org/t/external-dac/2820)._