LPC804 - Movable function in reduced power modes and ADC interrupts

arafathyasar24 — Thu, 23 Feb 2023 07:12:33 GMT

Hi Team,

We are evaluating the reduced power modes in LPC804. In the LPC804 datasheet it is mentioned as below

Taking PIO0_10/ADC_7 as an example

1) The term movable function means, configuring or reinitializing the Pin as PIO0_10 or ADC_7. Is the understanding correct?

2) As the deep sleep and power down mode does not support ADC wakeup, shall I use the pin as ADC7 during normal mode and can configure the same pin as PIO0_10 before entering into deep sleep or power down mode?

3) Still ADC7 will get input from ADC circuit and if I configure the pin as PIO0_10 in raising or falling edge will it detect the interrupt?

4) In the LPC804 SDK there is no example for the ADC interrupt with lower and upper threshold, will I get any reference for the same?

Thanks & Regards,

Yasar Arafath

Re: LPC804 - Movable function in reduced power modes and ADC interrupts

RaRo — Thu, 23 Feb 2023 21:23:04 GMT

Hello @arafathyasar24,

For a better understanding of this, we recommend you check the UM11065 (LPC804 User Manual).

Before answering you the questions, first let's define what a movable function and a fixed-pin function are:

In the UM11065 (LPC804 User Manual) Chapter 8: LPC804 Switch Matrix (SWM) [Section 8.4 General Description] states: "Most functions can be assigned through the switch matrix to any external pin that is not a power or ground pin. These functions are called movable functions." Some of them are: U0_TXD, U0_RXD, PLU_INPUT0, PLU_OUT0, etc.
Continues with: "A few functions like the analog comparator inputs can only be assigned to one particular external pin with the appropriate electrical characteristics. These functions are called fixed-pin functions." Like: ADC_7, ADC_6, RESETN, SWDIO, SWCLK, etc.

Now, let's go with your questions:

The term movable function means, configuring or reinitializing the Pin as PIO0_10 or ADC_7. Is the understanding correct?

Even though, there is a difference between the movable functions and the fixed-pins function, the datasheet means not use the pin for another functionality. So indeed, your understanding its correct. You should not configure trough the SWM ADC_7 functionality while using PIO0_10 for a wake-up from deep power-down mode.

As the deep sleep and power down mode does not support ADC wakeup, shall I use the pin as ADC7 during normal mode and can configure the same pin as PIO0_10 before entering into deep sleep or power down mode?

The ADC_7 actually is a fixed-pin function, the UM11065 states: "If a fixed-pin function is not used, it can be replaced by any other movable function." In subsection 8.4.2. Switch matrix register interface mentions: "If a fixed-pin function is deselected, any movable function can be assigned to its port and pin." So it might be possible to make the re-configuration you mention.

Related with the deep sleep mode, UM11065 Chapter 12: LPC804 Reduced power modes and power management says: "…WAKEUP pins can be used to wake up only from deep power-down mode…" not for deep sleep.

Still ADC7 will get input from ADC circuit and if I configure the pin as PIO0_10 in raising or falling edge will it detect the interrupt?

As long as you do not use the pin for both functionalities at the same time it should work. In deep power-down mode ADC is off, so both of the functionalities would not work.

[UM11065: Table 173. Peripheral configuration in reduced power modes]

In the LPC804 SDK there is no example for the ADC interrupt with lower and upper threshold, will I get any reference for the same?

Finally, the lpc_adc_burst and lpc_adc_interrupt examples have a compare threshold situation, that could be useful for you to test.

Best regards, Raul.

topic LPC804 - Movable function in reduced power modes and ADC interrupts in LPC Microcontrollers

LPC804 - Movable function in reduced power modes and ADC interrupts

Re: LPC804 - Movable function in reduced power modes and ADC interrupts