Addition of RS485 support

Author: mubes

ports/mimxrt10xx/common-hal/busio/UART.c

@@ -73,7 +73,8 @@ void LPUART_UserCallback(LPUART_Type *base, lpuart_handle_t *handle, status_t st
 
 void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
-        const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts, bool rs485_mode,
+        const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
+        const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
         uint32_t baudrate, uint8_t bits, uart_parity_t parity, uint8_t stop,
         mp_float_t timeout, uint16_t receiver_buffer_size) {
 
@@ -114,7 +115,22 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
         mp_raise_RuntimeError(translate("Invalid UART pin selection"));
     }
 
-    // Now check for RTS/CTS pin(s)
+    // Filter for sane settings for RS485
+    if (rs485_dir != mp_const_none) {
+      if ((rts != mp_const_none) || (cts != mp_const_none)) {
+        mp_raise_ValueError(translate("Cannot specify RTS or CTS in RS485 mode"));
+      }
+      // For IMXRT the RTS pin is used for RS485 direction
+      rts = rs485_dir;
+    }
+    else
+      {
+        if (rs485_invert == true) {
+          mp_raise_ValueError(translate("RS485 inversion specified when not in RS485 mode"));
+        }
+      }
+
+    // Now check for RTS/CTS (or overloaded RS485 direction) pin(s)
     const uint32_t rts_count = sizeof(mcu_uart_rts_list) / sizeof(mcu_periph_obj_t);
     const uint32_t cts_count = sizeof(mcu_uart_cts_list) / sizeof(mcu_periph_obj_t);
 
@@ -163,10 +179,24 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     config.enableTx = self->tx_pin != NULL;
     config.enableRx = self->rx_pin != NULL;
     config.enableRxRTS = self->rts_pin != NULL;
-    config.enableTxCTS = self->cts_pin != NULL;    
-    
+    config.enableTxCTS = self->cts_pin != NULL;
+    if (self->rts_pin != NULL)
+      claim_pin(self->rts_pin->pin);
+    if (self->cts_pin != NULL)
+      claim_pin(self->cts_pin->pin);
+
     LPUART_Init(self->uart, &config, UART_CLOCK_FREQ);
 
+    // Before we init, setup RS485 direction pin
+    // ..unfortunately this isn't done by the driver library
+    uint32_t modir = (self->uart->MODIR) & ~(LPUART_MODIR_TXRTSPOL_MASK | LPUART_MODIR_TXRTSE_MASK);
+    if (rs485_dir != mp_const_none) {
+      modir |= LPUART_MODIR_TXRTSE_MASK;
+      if ( rs485_invert == true )
+        modir |= LPUART_MODIR_TXRTSPOL_MASK;
+    }
+    self->uart->MODIR = modir;
+
     if (self->tx_pin != NULL)
       claim_pin(self->tx_pin->pin);
 

ports/mimxrt10xx/supervisor/flexspi_nor_flash_ops.c

@@ -324,7 +324,7 @@ void flexspi_nor_flash_init(FLEXSPI_Type *base)
     config.ahbConfig.enableAHBBufferable  = true;
     config.ahbConfig.enableReadAddressOpt = true;
     config.ahbConfig.enableAHBCachable    = true;
-    config.rxSampleClock                  = kFLEXSPI_ReadSampleClkLoopbackFromDqsPad;
+    config.rxSampleClock                  = kFLEXSPI_ReadSampleClkLoopbackInternally; //kFLEXSPI_ReadSampleClkLoopbackFromDqsPad;
     FLEXSPI_Init(base, &config);
 
     /* Configure flash settings according to serial flash feature. */

shared-bindings/busio/UART.c

@@ -53,6 +53,10 @@
 //|
 //|   :param ~microcontroller.Pin tx: the pin to transmit with, or ``None`` if this ``UART`` is receive-only.
 //|   :param ~microcontroller.Pin rx: the pin to receive on, or ``None`` if this ``UART`` is transmit-only.
+//|   :param ~microcontroller.Pin rts: the pin for rts, or ``None`` if rts not in use.
+//|   :param ~microcontroller.Pin cts: the pin for cts, or ``None`` if cts not in use.
+//|   :param ~microcontroller.Pin rs485_dir: the pin for rs485 direction setting, or ``None`` if rs485 not in use.
+//|   :param bool rs485_invert: set to invert the sense of the rs485_dir pin.
 //|   :param int baudrate: the transmit and receive speed.
 //|   :param int bits:  the number of bits per byte, 7, 8 or 9.
 //|   :param Parity parity:  the parity used for error checking.
@@ -82,7 +86,8 @@ STATIC mp_obj_t busio_uart_make_new(const mp_obj_type_t *type, size_t n_args, co
     // https://github.com/adafruit/circuitpython/issues/1056)
     busio_uart_obj_t *self = m_new_ll_obj(busio_uart_obj_t);
     self->base.type = &busio_uart_type;
-    enum { ARG_tx, ARG_rx, ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_timeout, ARG_receiver_buffer_size, ARG_rts, ARG_cts, ARG_rs485};
+    enum { ARG_tx, ARG_rx, ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_timeout, ARG_receiver_buffer_size,
+           ARG_rts, ARG_cts, ARG_rs485_dir,ARG_rs485_invert};
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_tx, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_rx, MP_ARG_REQUIRED | MP_ARG_OBJ },
@@ -94,7 +99,8 @@ STATIC mp_obj_t busio_uart_make_new(const mp_obj_type_t *type, size_t n_args, co
         { MP_QSTR_receiver_buffer_size, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 64} },
         { MP_QSTR_rts, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
         { MP_QSTR_cts, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
-        { MP_QSTR_rs485, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false } },
+        { MP_QSTR_rs485_dir, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none } },
+        { MP_QSTR_rs485_invert, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false } },
     };
     mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
     mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
@@ -131,9 +137,10 @@ STATIC mp_obj_t busio_uart_make_new(const mp_obj_type_t *type, size_t n_args, co
 
     const mcu_pin_obj_t* cts = MP_OBJ_TO_PTR(args[ARG_cts].u_obj);
 
-    bool rs485 = args[ARG_rs485].u_bool;
+    const mcu_pin_obj_t* rs485_dir = args[ARG_rs485_dir].u_obj;
+    bool rs485_invert = args[ARG_rs485_invert].u_bool;
 
-    common_hal_busio_uart_construct(self, tx, rx, rts, cts, rs485,
+    common_hal_busio_uart_construct(self, tx, rx, rts, cts, rs485_dir, rs485_invert,
                                     args[ARG_baudrate].u_int, bits, parity, stop, timeout,
                                     args[ARG_receiver_buffer_size].u_int);
     return (mp_obj_t)self;

shared-bindings/busio/UART.h

@@ -41,7 +41,8 @@ typedef enum {
 // Construct an underlying UART object.
 extern void common_hal_busio_uart_construct(busio_uart_obj_t *self,
     const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
-    const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts, bool rs485_mode,
+    const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
+    const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
     uint32_t baudrate, uint8_t bits, uart_parity_t parity, uint8_t stop,
     mp_float_t timeout, uint16_t receiver_buffer_size);
 

shared-module/board/__init__.c

@@ -111,12 +111,17 @@ mp_obj_t common_hal_board_create_uart(void) {
     const mcu_pin_obj_t* cts = mp_const_none;
 #endif
 #ifdef DEFAULT_UART_IS_RS485
-    const bool rs485 = true;
+    const mcu_pin_obj_t* rs485_dir = MP_OBJ_TO_PTR(DEFAULT_UART_BUS_RS485DIR);
+#ifdef DEFAULT_UART_RS485_INVERT
+    const bool rs485_invert = true;
+#endif
 #else
-    const bool rs485 = false;
+    const mcu_pin_obj_t* rs485_dir = mp_const_none;
+    const bool rs485_invert = true;
 #endif
 
-    common_hal_busio_uart_construct(self, tx, rx, rts, cts, rs485, 9600, 8, PARITY_NONE, 1, 1.0f, 64);
+    common_hal_busio_uart_construct(self, tx, rx, rts, cts, rs485_dir, rs485_invert,
+                                    9600, 8, PARITY_NONE, 1, 1.0f, 64);
     MP_STATE_VM(shared_uart_bus) = MP_OBJ_FROM_PTR(self);
     return MP_STATE_VM(shared_uart_bus);
 }