Enabling UART disables the Radio

[ABHarr]

Hi,

I am using the nRF52832 and am going at it barebones because I cannot for the life of me get the SDK to work. I am using the nRF52832 manual.

-> Manual

I have two boards and I have them configured one as transmitter and one as receiver.

Receiver Initialization:

NRF_CLOCK->TASKS_HFCLKSTART = 1; 
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

NRF_RADIO->POWER = 1; /* Turn the radio on */
NRF_RADIO->MODE = RADIO_MODE_MODE_Nrf_2Mbit << RADIO_MODE_MODE_Pos; /* BLE mode */
NRF_RADIO->PCNF0 = 0; /* no S0, S1 or length fields. 8-bit preamble. */
NRF_RADIO->PCNF1 = (16 << RADIO_PCNF0_LFLEN_Pos) | /* Packet Length */
(16 << RADIO_PCNF1_STATLEN_Pos) | /* Static Length Parameter in number of Bytes */
(2 << RADIO_PCNF1_BALEN_Pos) | /* Base Address Length in number of Bytes */
(RADIO_PCNF1_ENDIAN_Little << RADIO_PCNF1_ENDIAN_Pos) | /* Little Endian */
(RADIO_PCNF1_WHITEEN_Enabled << RADIO_PCNF1_WHITEEN_Pos); /* Enable Packet whitening? */
NRF_RADIO->DATAWHITEIV = 0x55; /* Init whitening value */

NRF_RADIO->BASE0 = 0x0000BABE; /* Configure BASE0 */
NRF_RADIO->PREFIX0 = 0x41 << RADIO_PREFIX0_AP0_Pos; /* Configure Prefix0 */

NRF_RADIO->RXADDRESSES = RADIO_RXADDRESSES_ADDR0_Enabled << RADIO_RXADDRESSES_ADDR0_Pos; /* Use Logical Address (BASE0 + PREFIX0 byte 0)*/


NRF_RADIO->CRCCNF = (RADIO_CRCCNF_LEN_Two << RADIO_CRCCNF_LEN_Pos) | /* Initialize CRC (two bytes) */
(RADIO_CRCCNF_SKIPADDR_Skip << RADIO_CRCCNF_SKIPADDR_Pos);
NRF_RADIO->CRCPOLY = 0x0000AAAA;
NRF_RADIO->CRCINIT = 0x12345678;

NRF_RADIO->MODECNF0 = (RADIO_MODECNF0_DTX_B0 << RADIO_MODECNF0_DTX_Pos) | /* Enable Fast Ramp Up */
(RADIO_MODECNF0_RU_Fast << RADIO_MODECNF0_RU_Pos);

NRF_RADIO->FREQUENCY = 0 << RADIO_FREQUENCY_FREQUENCY_Pos; /* receiving/sending packets at 2400MHz */

NRF_RADIO->PACKETPTR = (uint32_t)&packet[0]; /* Configure address of the packet and logic address to use */

NRF_RADIO->SHORTS = (RADIO_SHORTS_READY_START_Enabled << RADIO_SHORTS_READY_START_Pos) | /* Configure shortcuts to start as soon as READY event is received, and disable radio as soon as packet is received. */
(RADIO_SHORTS_END_DISABLE_Enabled << RADIO_SHORTS_END_DISABLE_Pos);

Transmitter Initialization:

NRF_CLOCK->TASKS_HFCLKSTART = 1; /* Start the HFCLK from crystal oscillator. */
while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);

NRF_RADIO->POWER = 1; /* Turn the radio on */

NRF_RADIO->MODE = RADIO_MODE_MODE_Nrf_2Mbit << RADIO_MODE_MODE_Pos; /* configure for BLE mode */

NRF_RADIO->PCNF0 = 0; /* No S0, S1, or Length fields. 8-bit preamble */
NRF_RADIO->PCNF1 = (16 << RADIO_PCNF1_MAXLEN_Pos) | /* Packet Length */
(16 << RADIO_PCNF1_STATLEN_Pos) | /* Static Length Parameter in number of Bytes */
(2 << RADIO_PCNF1_BALEN_Pos) | /* Base Address Length in number of Bytes */
(RADIO_PCNF1_ENDIAN_Little << RADIO_PCNF1_ENDIAN_Pos) | /* Little Endian */
(RADIO_PCNF1_WHITEEN_Enabled << RADIO_PCNF1_WHITEEN_Pos); /* Enable Packet whitening? */

NRF_RADIO->DATAWHITEIV = 0x55; /* Init whitening value*/

NRF_RADIO->BASE0 = 0x0000BABE; /* Configure Base0 */
NRF_RADIO->PREFIX0 = 0x41 << RADIO_PREFIX0_AP0_Pos; /* Configure Address prefix */

NRF_RADIO->TXADDRESS = 0 << RADIO_TXADDRESS_TXADDRESS_Pos; /* Use logical address 0 (BASE0 + PREFIX byte 0)*/

NRF_RADIO->MODECNF0 = (RADIO_MODECNF0_DTX_B0 << RADIO_MODECNF0_DTX_Pos) | /* Enable fast rampup, new in nRF52 */
(RADIO_MODECNF0_RU_Fast << RADIO_MODECNF0_RU_Pos);

NRF_RADIO->TXPOWER = RADIO_TXPOWER_TXPOWER_Pos4dBm << RADIO_TXPOWER_TXPOWER_Pos; /* 4dBm output power, sending packets at 2400MHz */
NRF_RADIO->FREQUENCY = 0 << RADIO_FREQUENCY_FREQUENCY_Pos;

NRF_RADIO->PACKETPTR = (uint32_t)&packet[0]; /* Configure address of the packet and logic address to use */

NRF_RADIO->SHORTS = (RADIO_SHORTS_READY_START_Enabled << RADIO_SHORTS_READY_START_Pos) | /* Configure shortcuts to start as soon as READY event is received, and disable radio as soon as packet is sent. */
(RADIO_SHORTS_END_DISABLE_Enabled << RADIO_SHORTS_END_DISABLE_Pos);

When I try to enable UART (which I know works because I got it working on its own), the receiver just doesn't work. I toggle an LED for when each is transmitting/receiving. The LED on the receiver never toggles. Is there something about using the radio and UART0 together that doesn't work?

UART init for completeness:

NRF_P0->PIN_CNF[27] = 0x02 | 0x01;
NRF_P0->DIRSET |= GPIO_PIN27_Msk;
NRF_P0->OUTSET |= GPIO_PIN27_Msk;
NRF_P0->PIN_CNF[26] = 0;
NRF_P0->DIRCLR |= GPIO_PIN26_Msk;
NRF_P0->OUTCLR |= GPIO_PIN26_Msk;

NRF_UARTE0->ENABLE = 0; /* Disable UARTE0 */

NRF_UART0->PSELTXD &= ~GPIO_PIN27_Msk;
NRF_UART0->PSELRXD &= ~GPIO_PIN26_Msk;
NRF_UART0->BAUDRATE = UART_Baud9600;
NRF_UART0->CONFIG = 0;
NRF_UART0->ENABLE = 0x04;

[hmolesworth]

Try replacing

NRF_UART0->PSELTXD &= ~GPIO_PIN27_Msk;
NRF_UART0->PSELRXD &= ~GPIO_PIN26_Msk;

with

NRF_UART0->PSELTXD = 27;
NRF_UART0->PSELRXD = 26;

assuming Tx is on pin 27 and Rx on pin 26 of course.

As an aside, mixing UART0 and UARTE0 is best avoided, even though they are the same physical address it makes the code confusing to review.

[ABHarr]

No idea why this worked but thank you. I never would have gotten that on my own.

[hmolesworth]

Nice, you're welcome. In the code you were using both Tx and Rx were being set to pin P0.00 (~0x...1F), which happens to be the 32kHz crystal input pin (if enabled as such); I imagine the chip designers didn't plan on that, or Tx being connected to Rx :-)