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TMS320F280049M: AIO Pin in F280049

Bard Ciou
Intellectual 900 points

Part Number: TMS320F280049M

Dear All

I saw the AIO just support digital input in F28004x device.

In previous series that we support Input/output.

Its make customer confuse and hard to assign their pin allocation.

Many thanks.

  • 0
    TI__Guru 60865 points

    Hi Bard,

    The design does indeed only support input mode.

  • 0 in reply to Devin Cottier
    TI__Intellectual 900 points

    Hi Devin

    1. what is special analog mode?

    2. why modify it for what reasons?

    thanks.

  • 0 in reply to Bard Ciou
    TI__Guru 60865 points

    Hi Bard,

    GPIO22 and GPIO23 are used for the on-chip DC-DC converter (3.3V -> 1.2V).  They come up in this mode by default, but you can switch them to GPIO instead if desired.

    F28004x uses an architecture which can't support output mode.  Previous designs that had AIO with outputs (e.g. F2803x, F2806x) use a different analog architecture.  

  • 0 in reply to Devin Cottier
    TI__Intellectual 900 points
    Hi Devin,

    Thanks for your comment.
    for item 1).
    I know these 2 pin in the initial state connect to DCDC converter, how about the direction for these 2 pins (input / output) if output is high or low level?

    for item 2).
    Does team had any reasons why we changed the analog architecture since cost or any advantages?

    Thanks.
  • 0 in reply to Bard Ciou
    TI__Guru 60865 points

    Hi Bard,

    Both DC-DC pins should be High-Z by default, since the DC-DC is disabled on power-up until/unless enabled by software.

    As far as the new analog architecture, there are quite a few improvements.  Some of the most obvious would be:

    • ADC DC specifications are much improved (gain, offset, and linearity error)
    • ADC AC specifications are improved (SNR, THD, SFDR)
    • Some devices have 16-bit ADCs
    • Multiple ADC blocks allow support of 3x or 4x simultaneous sampling (vs 2x on legacy devices) depending on how many ADC modules are present
    • System ADC sampling throughput is increased (due to multiple ADC modules)
    • Devices now have buffered DACs
    • PGA performance and options have increased vs. F2805x
    • Many more comparators and comparator configuration options