MSP432 and TI-RTOS: another I2C example - talk to a DAC

RE: MSP432 and TI-RTOS: another I2C example - talk to a DAC

Jan Cumps — Sat, 04 Mar 2017 15:28:20 GMT

Somewhat related video:

[View:https://www.youtube.com/watch?v=WGfV5O3l5_8:597:448]

RE: MSP432 and TI-RTOS: another I2C example - talk to a DAC

Jan Cumps — Thu, 02 Mar 2017 17:39:08 GMT

A little more advanced use of i2c and TI-RTOS

Integration of a SCPI library that listens to commands from LabVIEW or PuTTY, and sets the output of the DAC as result.

This example uses RTOS events and mailbox system (also used in MSP432 and TI-RTOS: PID Library Part 1 - Intro). DAC task waits for a message to arrive, then sets output accordingly.

[View:/resized-image/__size/164x416/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-ac9ac63c-ba5d-4c7f-91b9-2e21fde9d2fd/3515.contentimage_5F00_183799.png:164:416]

protocol analyzer:

[View:/resized-image/__size/620x540/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-ac9ac63c-ba5d-4c7f-91b9-2e21fde9d2fd/8306.contentimage_5F00_183800.png:620:540]

Scope:

[View:/resized-image/__size/616x372/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-ac9ac63c-ba5d-4c7f-91b9-2e21fde9d2fd/2538.contentimage_5F00_183801.png:616:372]

RE: MSP432 and TI-RTOS: another I2C example - talk to a DAC

jc2048 — Wed, 01 Mar 2017 11:42:36 GMT

I don't understand why you're all fussing. The DAC doesn't have the drive that the processor does, but it's still registering an ACK successfully.

Much more importantly, when are we going to hear it playing a tune?

RE: MSP432 and TI-RTOS: another I2C example - talk to a DAC

Robert Peter Oakes — Wed, 01 Mar 2017 06:54:04 GMT

Well, I am happy to say it is not unique to your setup, here is what I am getting on the CPU side of the I2C bus using the MSP432, not so many spikes on the DAC output but still the runts etc on the data lines. it looks like there coinciding with the ack, the dac certainly is not being corrupted by it, and the scope is also ignoring it... thought ?

[View:/resized-image/__size/620x372/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-ac9ac63c-ba5d-4c7f-91b9-2e21fde9d2fd/5582.contentimage_5F00_183797.png:620:372]

its on every 9th bit... more like the ACK, perhaps a higher value pull up would reduce the effect ?

RE: MSP432 and TI-RTOS: another I2C example - talk to a DAC

Robert Peter Oakes — Tue, 28 Feb 2017 17:03:35 GMT

I cant help nut notice those runts on the channel 2 line, and also aligning with the "?" in the decode... any ideas, there probably aligning with the ack response with the I2C bus

I used the ISO1540 instead of the 1541 (I happened to have some), this may help with this too as the 1540 is 2 channel bi directional vs just one of them, aside from that there pin compatable.