Hello
I would like use at least 2PPI channels to control a GPIO.
If PPI CH0&CH1 both setup, then GPIO_CTL just go high.
If PPI CH0 remarked, then GPIO_CTL go low
How to use 2ppi to control 1gpio?
The code as below
uint32_t PPI_evt_addr; uint32_t PPI_task_addr; nrf_ppi_channel_t ppi_channel; /* PPI CHANNEL0 SETUP */ ppi_channel=NRF_PPI_CHANNEL0; nrf_drv_gpiote_out_config_t config_1=GPIOTE_CONFIG_OUT_TASK_HIGH; nrf_drv_gpiote_out_init(GPIO_CTL , &config_1); nrf_drv_ppi_channel_alloc(&ppi_channel); PPI_evt_addr = nrf_drv_timer_event_address_get(&TIMER1, NRF_TIMER_EVENT_COMPARE0); PPI_task_addr = nrf_drv_gpiote_out_task_addr_get(GPIO_CTL); nrf_drv_ppi_channel_assign(ppi_channel, PPI_evt_addr, PPI_task_addr); nrf_drv_ppi_channel_enable(ppi_channel); nrf_drv_gpiote_out_task_enable(GPIO_CTL); /* PPI CHANNEL1 SETUP */ ppi_channel=NRF_PPI_CHANNEL1; nrf_drv_gpiote_out_config_t config_0=GPIOTE_CONFIG_OUT_TASK_LOW; nrf_drv_gpiote_out_init(GPIO_CTL , &config_0); nrf_drv_ppi_channel_alloc(&ppi_channel); PPI_evt_addr = nrf_drv_timer_event_address_get(&TIMER2, NRF_TIMER_EVENT_COMPARE0); PPI_task_addr = nrf_drv_gpiote_out_task_addr_get(GPIO_CTL); nrf_drv_ppi_channel_assign(ppi_channel, PPI_evt_addr, PPI_task_addr); nrf_drv_ppi_channel_enable(ppi_channel); nrf_drv_gpiote_out_task_enable(GPIO_CTL);
Hello,
you cannot assign two GPIOTE channels to the same pin, that won't work. But you can control different tasks of a single GPIOTE channel (SET and CLR) from two different PPI channels.
Hi Dmitry
How to setup ""a single GPIOTE channel (SET and CLR) from two different PPI channels"?
My code as below. Thanks a lot.
NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[0]; NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; NRF_PPI->CH[1].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[1]; NRF_PPI->CH[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; NRF_PPI->CH[2].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[2]; NRF_PPI->CH[2].TEP = (uint32_t)&NRF_TIMER2->TASKS_STOP; // Stop TIMER NRF_PPI->CHEN = (PPI_CHEN_CH0_Enabled << PPI_CHEN_CH0_Pos) | (PPI_CHEN_CH1_Enabled << PPI_CHEN_CH1_Pos) | (PPI_CHEN_CH2_Enabled << PPI_CHEN_CH2_Pos); NRF_GPIOTE->CONFIG[0] =((GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |(CVSD_CTL << GPIOTE_CONFIG_PSEL_Pos) |(GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos) |(GPIOTE_CONFIG_OUTINIT_High << GPIOTE_CONFIG_OUTINIT_Pos));
Austin
For example, to make a low-polarity pulse:
NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[0]; NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_CLR[0]; NRF_PPI->CH[1].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[1]; NRF_PPI->CH[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_SET[0];
Thanks a lot! You rescue me!
If I use "(uint32_t)&NRF_GPIOTE->TASKS_OUT[0];" , it cost timing around 1us.
I use "(uint32_t)&NRF_GPIOTE->TASKS_CLR[0]; " or "(uint32_t)&NRF_GPIOTE->TASKS_SET[0];" , the timing cost is almost zero!
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I have a new problem as below.
void TIMER2_config(void) { NRF_TIMER2->TASKS_STOP = 1; // Stop timer NRF_TIMER2->MODE = TIMER_MODE_MODE_Timer; // taken from Nordic dev zone NRF_TIMER2->BITMODE = (TIMER_BITMODE_BITMODE_08Bit << TIMER_BITMODE_BITMODE_Pos); NRF_TIMER2->PRESCALER = 0; // 1us resolution NRF_TIMER2->TASKS_CLEAR = 1; // Clear timer NRF_TIMER2->CC[0] = 1; //*62.5ns NRF_TIMER2->CC[1] = 2; //*62.5ns NRF_TIMER2->CC[2] = 62; //*62.5ns NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos) | (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos) | (TIMER_INTENSET_COMPARE2_Enabled << TIMER_INTENSET_COMPARE2_Pos); // taken from Nordic dev zone NRF_TIMER2->SHORTS = (TIMER_SHORTS_COMPARE0_CLEAR_Disabled << TIMER_SHORTS_COMPARE0_CLEAR_Pos) | (TIMER_SHORTS_COMPARE1_CLEAR_Disabled << TIMER_SHORTS_COMPARE1_CLEAR_Pos) | (TIMER_SHORTS_COMPARE2_CLEAR_Enabled << TIMER_SHORTS_COMPARE2_CLEAR_Pos); }
void PPI_config(void) { /*when TIMER2 CC0 = NUM , then pin =0*/ NRF_PPI->CH[0].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[0]; // NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; NRF_PPI->CH[0].TEP = (uint32_t)&NRF_GPIOTE->TASKS_CLR[0]; /when TIMER2 CC1 = NUM , then pin = 1*/ NRF_PPI->CH[1].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[1]; // NRF_PPI->CH[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_OUT[0]; NRF_PPI->CH[1].TEP = (uint32_t)&NRF_GPIOTE->TASKS_SET[0]; /*when TIMER2 CC2 = NUM then TIMER2 stop*/ NRF_PPI->CH[2].EEP = (uint32_t)&NRF_TIMER2->EVENTS_COMPARE[2]; NRF_PPI->CH[2].TEP = (uint32_t)&NRF_TIMER2->TASKS_STOP; // Stop TIMER NRF_PPI->CHEN = (PPI_CHEN_CH0_Enabled << PPI_CHEN_CH0_Pos) | (PPI_CHEN_CH1_Enabled << PPI_CHEN_CH1_Pos) | (PPI_CHEN_CH2_Enabled << PPI_CHEN_CH2_Pos); NRF_GPIOTE->CONFIG[0] =((GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |(CVSD_CTL << GPIOTE_CONFIG_PSEL_Pos) |(GPIOTE_CONFIG_POLARITY_Toggle << GPIOTE_CONFIG_POLARITY_Pos) |(GPIOTE_CONFIG_OUTINIT_High << GPIOTE_CONFIG_OUTINIT_Pos)); }
int8_t bit_cnt; bit_cnt++; bit_cnt = bit_cnt & 0x01; bool DIN_bit ; DIN_bit = bit_cnt; //for test NRF_TIMER2->CC[0] = 1; NRF_TIMER2->CC[1] = 3; NRF_TIMER2->CC[2] = 62; nrf_gpio_pin_write (GPIO14, DIN_bit ); NRF_TIMER2->TASKS_START = 1; // Start TIMER
GPIO14 is a sign, for check how log PPI CH0 works.
The question is ,
After "NRF_TIMER2->TASKS_START = 1;", the timing pass 400ns then PPI CH0 works.
How could it takes so much time?
In my imagine, PPI CH0 should response in 100ns , because CC[0]=1.
I couldn't get your goal.. if you need to respond to an external signal as quick as possible, you should start a timer also using PPI, but if it's a response to a software event, you cannot guarantee such a tight timings. Your code is compiled into a sequence of assembly instructions, their count depends on compiler and its settings (especially optimization level), and they cannot be executed in a zero time. Also the timer needs some time to start up.