How does the LPC1788FBD144 chip configure the ADC function to collect two signals simultaneously?

[明杰周]

Now I need to configure the AD sampling feature of the LPC1788FBD144 chip, which requires the ability to read both signals simultaneously. However, there is only one ADC in the chip, how to sample two signals. By looking at the chip manual, you know that the chip has an ADC mouth with 8 channels at the same time. But in software mode, only one channel can be sampled at a time. If in the hardware scan mode, which bits of the 8 channels are set to 1, the sampling values of these channels can be read. I suspect that you may need to configure a hardware scan mode to sample both signals simultaneously.

My question is:

1、LPC1788FBD144 chip has only one ADC mouth, how to sample two signals simultaneously?

2、The first 8 bits in the AD control register of LPC chip are the selection and input channels. In the software mode, only one can be set to 1. In the hardware scan mode, any value containing 1-8 can be written into that bit. I now need to collect two signals, which will require two channels, so two channels must be configured in the hardware scan mode. So what is the hardware scan pattern? Which registers should I configure to start the hardware scan mode?

[jeremyzhou · Accepted solution]

Hi 明杰 周

Thank you for your interest in NXP Semiconductor products and 

the opportunity to serve you.

1) LPC1788FBD144 chip has only one ADC mouth, how to sample two signals simultaneously?

-- The ADC doesn't support sample sveral channels simultaneously, in hardware scan mode, the ADC converter will sample the channel in successive way when hardware achieves.

To configure hardware scan mode, the [26:24 ]Start bits should combine with [27]EDGE bits.

If the BURST bit in the ADCR is 0 and the START field contains 010-111, the ADC will

start a conversion when a transition occurs on a selected pin or Timer Match signal.

Hope this is clear.

Jeremy

Have a great day,
TIC

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[明杰周]

Thank you very much for your answer.I have some questions.

1)If the BURST bit in the ADCR is 1，So can we set the [7:0]SEL bits to 1 all of bits?

2)If the BURST bit in the ADCR is 1，Can we use multiple channels to collect several different signals?

3) If the BURST bit in the ADCR is 1,How to set [26:24]START bits and [27]EDGE bit ?

4)If the BURST bit in the ADCR is 1,Can the AD conversion be started when the chip is powered on?

[jeremyzhou]

Hi,

Thanks for your reply.

1)If the BURST bit in the ADCR is 1，So can we set the [7:0]SEL bits to 1 all of bits?

-- Yes

2)If the BURST bit in the ADCR is 1，Can we use multiple channels to collect several different signals?

 -- Yes

3) If the BURST bit in the ADCR is 1,How to set [26:24]START bits and [27]EDGE bit ?

-- START bits must be 000 when BURST = 1

4)If the BURST bit in the ADCR is 1,Can the AD conversion be started when the chip is powered on?

-- Yes.

Hope this is clear

Have a great day,
TIC

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