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With the old logic if Serial::writeable() was called before and/or used ... #778

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Dec 10, 2014
Merged

With the old logic if Serial::writeable() was called before and/or used ... #778

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With the old logic if Serial::writeable() was called before and/or us… 
…ed to block calls to Serial::putc() it would never write due to EVENT_TXDRDY trailing a write to TXD. Add a dummy write to TXD before pins are connected to the peripheral. This primes the EVENT_TXDRDY to lead future writes rather than trail. Since STOPTX isn't used this seems safe.
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@sg-
sg- committed Dec 9, 2014
commit 91a77d74cf70c2d8fb5b9d1ce186db44dcb0e4ba
4 changes: 2 additions & 2 deletions libraries/mbed/targets/cmsis/TARGET_NORDIC/TARGET_MCU_NRF51822/nrf51.h
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Original file line number Diff line number Diff line change
Expand Up @@ -376,7 +376,8 @@ typedef struct { /*!< UART Structure
__IO uint32_t EVENTS_RXTO; /*!< Receiver timeout. */
__I uint32_t RESERVED5[46];
__IO uint32_t SHORTS; /*!< Shortcuts for TWI. */
__I uint32_t RESERVED6[64];
__I uint32_t RESERVED6[63];
__IO uint32_t INTEN; /*!< Interrupt enable register. */
__IO uint32_t INTENSET; /*!< Interrupt enable set register. */
__IO uint32_t INTENCLR; /*!< Interrupt enable clear register. */
__I uint32_t RESERVED7[93];
Expand Down Expand Up @@ -1213,4 +1214,3 @@ typedef struct { /*!< GPIO Structure


#endif /* nRF51_H */

36 changes: 19 additions & 17 deletions libraries/mbed/targets/hal/TARGET_NORDIC/TARGET_MCU_NRF51822/serial_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56,20 +56,12 @@ void serial_init(serial_t *obj, PinName tx, PinName rx) {
obj->uart = (NRF_UART_Type *)uart;

//pin configurations --
//outputs
NRF_GPIO->DIR |= (1 << tx); //TX_PIN_NUMBER);
NRF_GPIO->DIR |= (1 << RTS_PIN_NUMBER);

NRF_GPIO->DIR &= ~(1 << rx); //RX_PIN_NUMBER);
NRF_GPIO->DIR &= ~(1 << CTS_PIN_NUMBER);

obj->uart->PSELRTS = RTS_PIN_NUMBER;
obj->uart->PSELTXD = tx; //TX_PIN_NUMBER;

//inputs
obj->uart->PSELCTS = CTS_PIN_NUMBER;
obj->uart->PSELRXD = rx; //RX_PIN_NUMBER;


// set default baud rate and format
serial_baud (obj, 9600);
Expand All @@ -79,8 +71,16 @@ void serial_init(serial_t *obj, PinName tx, PinName rx) {
obj->uart->TASKS_STARTTX = 1;
obj->uart->TASKS_STARTRX = 1;
obj->uart->EVENTS_RXDRDY = 0;
// dummy write needed or TXDRDY trails write rather than leads write.
// pins are disconnected so nothing is physically transmitted on the wire
obj->uart->TXD = 0;

obj->index = 0;

obj->uart->PSELRTS = RTS_PIN_NUMBER;
obj->uart->PSELTXD = tx; //TX_PIN_NUMBER;
obj->uart->PSELCTS = CTS_PIN_NUMBER;
obj->uart->PSELRXD = rx; //RX_PIN_NUMBER;

// set rx/tx pins in PullUp mode
if (tx != NC) {
Expand Down Expand Up @@ -194,24 +194,27 @@ void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable)
if (enable) {
switch (irq) {
case RxIrq:
obj->uart->INTENSET |= (UART_INTENSET_RXDRDY_Msk);
obj->uart->INTEN |= (UART_INTENSET_RXDRDY_Msk);
break;
case TxIrq:
obj->uart->INTENSET |= (UART_INTENSET_TXDRDY_Msk);
obj->uart->INTEN |= (UART_INTENSET_TXDRDY_Msk);
break;
}
NVIC_SetPriority(irq_n, 3);
NVIC_EnableIRQ(irq_n);
} else { // disable
// maseked writes to INTENSET dont disable and masked writes to
// INTENCLR seemed to clear the entire register, not bits.
// Added INTEN to memory map and seems to allow set and clearing of specific bits as desired
int all_disabled = 0;
switch (irq) {
case RxIrq:
obj->uart->INTENSET &= ~(UART_INTENSET_RXDRDY_Msk);
all_disabled = (obj->uart->INTENSET & (UART_INTENSET_TXDRDY_Msk))==0;
obj->uart->INTEN &= ~(UART_INTENCLR_RXDRDY_Msk);
all_disabled = (obj->uart->INTENCLR & (UART_INTENCLR_TXDRDY_Msk)) == 0;
break;
case TxIrq:
obj->uart->INTENSET &= ~(UART_INTENSET_TXDRDY_Msk);
all_disabled = (obj->uart->INTENSET & (UART_INTENSET_RXDRDY_Msk))==0;
obj->uart->INTEN &= ~(UART_INTENCLR_TXDRDY_Msk);
all_disabled = (obj->uart->INTENCLR & (UART_INTENCLR_RXDRDY_Msk)) == 0;
break;
}

Expand All @@ -236,12 +239,11 @@ int serial_getc(serial_t *obj)

void serial_putc(serial_t *obj, int c)
{
obj->uart->TXD = (uint8_t)c;

while (!serial_writable(obj)) {
}

obj->uart->EVENTS_TXDRDY = 0;
obj->uart->TXD = (uint8_t)c;
}

int serial_readable(serial_t *obj)
Expand All @@ -251,7 +253,7 @@ int serial_readable(serial_t *obj)

int serial_writable(serial_t *obj)
{
return (obj->uart->EVENTS_TXDRDY ==1);
return (obj->uart->EVENTS_TXDRDY == 1);
}

void serial_break_set(serial_t *obj)
Expand Down