MPC5xxxのトピックRe: MPC5775K_356DS

MPC5775K_356DS

chenmiao — Thu, 26 May 2016 07:07:05 GMT

In the example of MPC5775K-ADC_example-S32DS.I see a segment :ETIMER_1.ENBL.R = 0x0;and there are lots of similar segments :ETIMER_1.CH[2].CMPLD1.R = (uint16_t) ADC_1.CDR[0].B.CDATA;I want to know what is the meaning of the last letter ‘ R’.

I have bought the daughter card MPC5775K_356DS. But I don't have the Reference manual of MPC5775K. So I don't know the range of the ADC . At J20 ,the names of SD ADC are SD_1_ADCN and SD_1_ADCP ,I consider 'N' and 'P' as negative and positive .So can I take sample of negative voltage??

I use the example of MPC5775K-ADC_example-S32DS. But the ADC_interrupt seems not to be automatically invoked or triggered. and I only can sample the value of the first point,other points are '0'. Why?How to sample the complete signal?And how to view the graph of the sample table?

The ADC of the MPC5775K seems to have two mod : SAR and sigdet .How to configure the mod sigdet?

Re: MPC5775K_356DS

martin_kovar — Thu, 26 May 2016 09:08:47 GMT

Letter R determines the access to the register. You can use B letter and specify the part of the register you want to access or you can use R letter and access to the whole register.

For example:

ADC_1.MCR.B.PWDN = 1; //disable ADC_1 ...this code writes 1 only to the PWDN bit

ADC_1.MCR.R = 0x00000001; //this code also writes 1 to PWDN bit, but also writes zeros to the rest of the register

For more information, how to access registers, please look at the following Engineering Bulletin:

http://cache.nxp.com/files/32bit/doc/eng_bulletin/EB758.pdf?fsrch=1&sr=1&pageNum=1

About reference manual for MPC5775K it is under NDA at this time. If you have already signed an agreement, please contact the person who assisted you. If you have not signed an agreement, please contact your local NXP Distributor Salesperson or FAE for assistance.

For a listing of our distributors, refer to:
http://www.nxp.com/buy/distributor-network:DISTRIBUTORS

MPC5775K has four 12-bit SAR ADC modules and one 12-bit SD ADC. Letters N and P should mean Normal and Precise. It determines the precision of ADC channel.

The example you mean continuously convert voltage from output of the trimmer placed on MPC57xx Motherboard. It means you get new value in every sampling period. This value is sent to Etimer to determine the duty cycle of PWM signal.So the full signal is converted, because of scan mode of ADC.

I do not know what you mean by "graph of the sample table". I do not save the converted values to create any table. I send them directly, to Etimer in the ADC interrupt.

About sigma delta ADC, we do not have any example. SD ADC is part of AFE module, which is too complex to create some simple example.

Regards,

Martin

Re: MPC5775K_356DS

chenmiao — Thu, 26 May 2016 13:13:29 GMT

Can I see the graph of the full signal in S32?

Re: MPC5775K_356DS

martin_kovar — Thu, 26 May 2016 13:17:16 GMT

Hi,

no it is not possible. S32 does not provide this functionality.

Regards,

Martin

Re: MPC5775K_356DS

chenmiao — Thu, 26 May 2016 13:58:54 GMT

How can I view all of the values sent to Etimer?not one value at the breakpoint I set

Re: MPC5775K_356DS

martin_kovar — Fri, 27 May 2016 07:43:07 GMT

Hi,

You cannot see all values, because these values are not saved in my example. If you want to see all values, you have to save them to memory. But there should be a problem, because sampling frequency is 250KHz so you will have 250 000 samples per second. One sample is 16-bit long.

Simple calculation 250 000 samples * 2 bytes = 488KB data every second.

If you want to view all values and see the signal waveform, you can use FreeMASTER. Please look at the following link:

Let´s start with FreeMASTER!

But from my point of view, you should decrease ADC sampling frequency because of amount of the data.

Regards,

Martin