Forums

ADC usage

Started by sowmya_gk November 28, 2004

Respected Sir/Madam,
we are working on a project which has 56f805 DSP on the EVM
kit. we're new to embedded field.
we have a few queries which need to be cleared to start our project.
kindly help us by doing the need.
The queries are as follows:
1. A basic sample program to use ADC, along with the connections
specified.
2. how to access the result registers to watch the digital outputs?
3. Detailed working of ADC.
4. Whatz the meaning of 8.5 ADC clock cycles, 26.5 ADC clock cycles?
5. differences b/w sequential, simultaneous modes and single ended,
differential i/ps and how are these related to each other.
6. How to use ADC channel list registers?

we have the following pdf files - 56f80x Users Manual, Data
sheets, EVMUM
But we are finding it difficult to find answers to these questions.
plz help us out as we are not able to proceed further in our project.
we will be grateful to u.
Thanking U,

Regards,
Sowmya and Devika.




Dear Sowmya and Devika,
the better place to look for informations on ADC is the user manual: DSP80F801-7UM;
You have there answers to all your questions.
For instance, a single conversion takes 8.5 of the ADC clock cycles; the following conversion will take only 6 cycles, yielding 14.5 cycles for the 2 conversions (or the 4 conversions if the 2 channels of the ADC are working). Thus 4 conversions (or 8 ) will take 26.5 cycles).
 
 This can work, but has many instructions you will find useless.
// Initialisation ADC
 move #$0004,x:$0E81
 move #$0000,x:$0E82
 move #$0010,x:$0E83 // 000 (AN0) and 001 (AN1) slots 0 and 1
 move #$0000,x:$0E84 // for converting only AN0 and AN1
 move #$00FC,x:$0E85 // inhibition other ch than 0 and 1
 move #$0000,x:$0E91 // limit inf: 0 for AN0
 move #$0000,x:$0E92 // limit inf: 0 for AN1
 move #$7FF8,x:$0E99 // limit sup: 0 for AN0
 move #$7FF8,x:$0E9A // limit sup: 0 for AN1
 move #$0000,x:$0EA1 // offset 0 for AN0
 move #$0000,x:$0EA2 // offset 0 for AN1
 
// Read ADC
 move #$3002,x:$0E80 // init a cv if not done
cv: move x:$0E86,x0 // raed stat register
 bftsth #0001,x0
 bcc cv //  end conversion? no wait at cv
 move x:$0E89,x0 // yes: read ADC 0
 asr x0 // remove the 3 LSB (they means nothing)
 asr x0
 asr x0
Regards.
 

sowmya_gk <s...@vsnl.net> wrote:


Respected Sir/Madam,
we are working on a project which has 56f805 DSP on the EVM
kit. we're new to embedded field.
we have a few queries which need to be cleared to start our project.
kindly help us by doing the need.
The queries are as follows:
1. A basic sample program to use ADC, along with the connections
specified.
2. how to access the result registers to watch the digital outputs?
3. Detailed working of ADC.
4. Whatz the meaning of 8.5 ADC clock cycles, 26.5 ADC clock cycles?
5. differences b/w sequential, simultaneous modes and single ended,
differential i/ps and how are these related to each other.
6. How to use ADC channel list registers?

we have the following pdf files - 56f80x Users Manual, Data
sheets, EVMUM
But we are finding it difficult to find answers to these questions.
plz help us out as we are not able to proceed further in our project.
we will be grateful to u.
Thanking U,

Regards,
Sowmya and Devika.------------------------ Yahoo! Groups Sponsor --------------------~-->
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hi!i am also newbie in dsp(i have 8323 dev. board but
their ADC is similar to yours...)
the number of replies in this group not much for a
long time...i'll try to answer as i can...
in the peripheral user manual you can find enough
information for questions 3,4 and 5...

single ended means adc will convert the voltage on the
ADC input pin(this is normal operation you know)...

in diferantial mode adc will convert the difference
betveen 2 input..

there is two adc mudule and in simulteneous mode
both of them works in same time...
in sequential mode you can use just 1 adc module
acording to adc pin that you use....

firsly you use metrowerk code warrior...
and processor expert -PE- embedden inside of it...
you can use PE to initalize your ADC...
and looking at to generated code by PE you can
understant how to acces ADC registers...
there is two way to acces peripherel register...you
can use PE PESL functions(more effective) and you can
use c functions like getREG16();..for example to acces
result register use
getReg16(ADCA_ADRSLT0);

for the register names look at the inside of #include
"IO_Map.h"...

in 56f8323 ADC clock 5MHz..this information is in
peripheral user manuel...so 8.5 adc clock cycle 1,7
us... isa
--- sowmya_gk <> wrote:

>
> Respected Sir/Madam,
> we are working on a project which has 56f805 DSP on
> the EVM
> kit. we're new to embedded field.
> we have a few queries which need to be cleared to
> start our project.
> kindly help us by doing the need.
> The queries are as follows:
> 1. A basic sample program to use ADC, along with the
> connections
> specified.
> 2. how to access the result registers to watch the
> digital outputs?
> 3. Detailed working of ADC.
> 4. Whatz the meaning of 8.5 ADC clock cycles, 26.5
> ADC clock cycles?
> 5. differences b/w sequential, simultaneous modes
> and single ended,
> differential i/ps and how are these related to each
> other.
> 6. How to use ADC channel list registers?
>
> we have the following pdf files - 56f80x Users
> Manual, Data
> sheets, EVMUM
> But we are finding it difficult to find answers to
> these questions.
> plz help us out as we are not able to proceed
> further in our project.
> we will be grateful to u.
> Thanking U,
>
> Regards,
> Sowmya and Devika. >
>

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