Interfacing ADS7888 (clocked at 16 Mhz) with an 8Mhz microcontroller

Sahil Jain

Other Parts Discussed in Thread: ADS7888, TLV571

Hi,

I would like to use an ADS7888 ADC, with a conversion rate of 1MSPS, and interface it with an 8Mhz microcontroller. I understand that I cannot connect the ADC serially to the micro, since the ADC is operating at a much higher clock speed (16 MHz).

One solution I came up with was to use a shift register (2 cascaded 8-bit shift registers in this case, since a conversion requires 16 cycle,s and outputs 4 binary values before and after the actual converted value) to hold the data, and then transfer it to the micro in parallel once the conversion has completed.

Would anyone be able to comment whether such a design is feasible, and whether the timing requirements might give me issues (i.e. the bits containing the converted values in the shift registers varying per conversion)?

Thanks,

Sahil

over 15 years ago

0 Tom Hendrick over 15 years ago

TI__Guru**** 181001 points

Hi Sahil,

What micro are you trying to talk to? The timing requirements would really depend on the device you are trying to use the collect the data. Does this micro have a true external parallel data bus or are you going to attempt to do 'port reads' to try and capture data?

0 Sahil Jain over 15 years ago in reply to Tom Hendrick

Prodigy 50 points

Hi Tom,

I apologise for the tardy response - I was expecting an email to inform me someone had replied!

I am using an ATmega8 MCU for data storage (as I am familiar with this MCU). I was going to use some cascaded serial-to-parallel converters, so that I could read in the entire serial data into a port at once (i.e. a single clock cycle). However, in the interest of ease of design, I have opted for a parallel ADC (TLV571).

Regards,

Sahil

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Interfacing ADS7888 (clocked at 16 Mhz) with an 8Mhz microcontroller