Add I2C target config and example.

Author: microbit-carlos

custom_targets.json

@@ -7,9 +7,13 @@
             "MCU_NRF52833"
         ],
         "static_memory_defines": false,
+        "device_has_add": [
+            "I2CSLAVE"
+        ],
         "macros_add": [
             "TARGET_MCU_NRF52833",
             "NRFX_RNG_ENABLED=1",
+            "NRFX_TWIS_ENABLED=1",
             "RNG_ENABLED=1",
             "NRF_QUEUE_ENABLED=1"
         ],

examples/i2c_target.cpp

@@ -0,0 +1,174 @@
+/*
+ * Copyright 2022 Micro:bit Educational Foundation and contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "mbed.h"
+#include "nrf_delay.h"
+
+#if !DEVICE_I2CSLAVE
+  #error [NOT_SUPPORTED] I2C Target mode is not supported
+#endif
+
+#define BUTTON_PRESSED  0
+
+
+/*****************************************************************************/
+/* Serial                                                                   */
+/*****************************************************************************/
+UnbufferedSerial pc(CONSOLE_TX, CONSOLE_RX, 115200);
+
+FileHandle *mbed::mbed_override_console(int fd) {
+    return &pc;
+}
+
+/*****************************************************************************/
+/* I2C data to send between devices                                          */
+/*****************************************************************************/
+#define TARGET_ADDR_8BIT (0xA0 << 1)
+const char MSG[] = "Slave!";
+const uint8_t MSG_LEN = 7;
+
+/*****************************************************************************/
+/* LED functions                                                             */
+/*****************************************************************************/
+void conf_op_pin(PinName pin) {
+    nrf_gpio_cfg(pin,
+        NRF_GPIO_PIN_DIR_OUTPUT,
+        NRF_GPIO_PIN_INPUT_DISCONNECT,
+        NRF_GPIO_PIN_NOPULL,
+        NRF_GPIO_PIN_H0H1,
+        NRF_GPIO_PIN_NOSENSE);
+}
+
+void set_led_1(bool set) {
+    set ? nrf_gpio_pin_clear(COL_1) : nrf_gpio_pin_set(COL_1);
+}
+
+void set_led_2(bool set) {
+    set ? nrf_gpio_pin_clear(COL_2) : nrf_gpio_pin_set(COL_2);
+}
+
+void leds_init() {
+    conf_op_pin(COL_1);
+    nrf_gpio_pin_clear(COL_1);
+    conf_op_pin(COL_2);
+    nrf_gpio_pin_clear(COL_2);
+    conf_op_pin(ROW_1);
+    nrf_gpio_pin_set(ROW_1);
+    set_led_1(false);
+    set_led_2(false);
+}
+
+void error_loop() {
+    while(1) {
+        set_led_1(true);
+        set_led_2(false);
+        nrf_delay_ms(250);
+        set_led_1(false);
+        set_led_2(true);
+        nrf_delay_ms(250);
+    }
+}
+
+/*****************************************************************************/
+/* I2C functions                                                             */
+/*****************************************************************************/
+void test_master() {
+    I2C controller(I2C_SDA1, I2C_SCL1);
+
+    uint8_t rxData[MSG_LEN] = { 0 };
+    int result = 0;
+
+    while (true) {
+        const uint8_t I2C_MSG_SLEEP = 0xAB;
+        uint8_t txData[1] = { I2C_MSG_SLEEP };
+        result = controller.write(TARGET_ADDR_8BIT, (char *)&txData, 1, false);
+        if (result != 0) {
+            printf("Write error: %d\n", result);
+            return;
+        }
+
+        result = controller.read(TARGET_ADDR_8BIT, (char *)&rxData, MSG_LEN);
+        if (result != 0) {
+            printf("Read error: %d\n", result);
+            return;
+        }
+        for (uint8_t i = 0; i < MSG_LEN; i++) {
+            if (rxData[i] != MSG[i]) {
+                printf("Message unexpected at chacter %d\n", i);
+                printf("Read buffer: %s\n", rxData);
+                return;
+            }
+            rxData[i] = 0;    // Reset it for next iteration
+        }
+        nrf_delay_ms(250);
+    }
+}
+
+
+void test_slave() {
+    I2CSlave target(I2C_SDA1, I2C_SCL1);
+    target.address(TARGET_ADDR_8BIT);
+
+    char buf[10];
+    while (true) {
+        int i = target.receive();
+        switch (i) {
+            case I2CSlave::ReadAddressed:
+                target.write(MSG, MSG_LEN);
+                printf("Received a read command");
+               break;
+            case I2CSlave::WriteGeneral:
+                target.read(buf, 10);
+                printf("Read General: %s\n", buf);
+                break;
+            case I2CSlave::WriteAddressed:
+                target.read(buf, 10);
+                printf("Read Address: %s\n", buf);
+                break;
+        }
+        for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
+    }
+}
+
+/*****************************************************************************/
+/* main                                                                      */
+/*****************************************************************************/
+int main(void) {
+    printf("I2C programme starting.\r\n");
+
+    DigitalIn buttonA(BUTTONA);
+    DigitalIn buttonB(BUTTONB);
+
+    leds_init();
+
+    while (true) {
+        if (buttonA == BUTTON_PRESSED) {
+            printf("MAIN device\r\n");
+            set_led_1(true);
+            test_master();
+            break;
+        }
+        if (buttonB == BUTTON_PRESSED) {
+            printf("SECONDARY device\r\n");
+            set_led_2(true);
+            test_slave();
+            break;
+        }
+    }
+
+    // test functions only return on failure
+    error_loop();
+}