1 files changed, 72 insertions, 0 deletions
diff --git a/main/pbdrv.c b/main/pbdrv.c
new file mode 100644
index 0000000..9d9e499
--- /dev/null
+++ b/main/pbdrv.c
@@ -0,0 +1,72 @@
+#include "pbdrv.h"
+
+#include "pb.h"
+#include "pb-types.h"
+#include "pb-mod.h"
+
+#include <hardware/i2c.h>
+#include <hardware/gpio.h>
+#include <pico/i2c_slave.h>
+
+#include <FreeRTOS.h>
+#include <timers.h>
+
+#define PBDRV_I2C i2c0
+#define BUF_SIZE 256
+#define MSGS_MAX 4
+
+typedef struct {
+	uint8_t data[BUF_SIZE];
+	size_t size;
+} i2c_msg_buf_t;
+
+static i2c_msg_buf_t msgs[MSGS_MAX];
+static size_t msg_index = 0;
+
+static void async_pbdrv_i2c_recv(void * _msg, uint32_t _) {
+	i2c_msg_buf_t * msg = _msg;
+	pbdrv_i2c_recv(msg->data, msg->size);
+}
+
+static void msg_complete(i2c_msg_buf_t * msg) {
+	// defer pbdrv_i2c_recv call to FreeRTOS scheduler as pbdrv_i2c_recv takes
+	// too long to return from an ISR
+	xTimerPendFunctionCallFromISR(async_pbdrv_i2c_recv, msg, 0, NULL);
+
+	// prepare next message for use
+	msg_index = (msg_index + 1) % MSGS_MAX;
+	msgs[msg_index].size = 0;
+}
+
+// This function is called from the I2C ISR
+static void recv_event(i2c_inst_t *i2c, i2c_slave_event_t event) {
+	i2c_msg_buf_t * msg = &msgs[msg_index];
+
+	switch (event) {
+		case I2C_SLAVE_RECEIVE: {
+			if (msg->size == BUF_SIZE) return;
+			msg->data[msg->size++] = i2c_read_byte_raw(PBDRV_I2C);
+			break;
+		}
+		case I2C_SLAVE_FINISH: {
+			msg_complete(msg);
+			break;
+		}
+		default: break;
+	}
+}
+
+void pbdrv_setup() {
+	i2c_init(PBDRV_I2C, PB_CLOCK_SPEED_HZ);
+	i2c_slave_init(PBDRV_I2C, PBDRV_MOD_ADDR, &recv_event);
+}
+
+__weak void pbdrv_i2c_send(i2c_addr_t addr, const uint8_t * buf, size_t sz) {
+	i2c_set_slave_mode(PBDRV_I2C, false, PBDRV_MOD_ADDR);
+
+	// false to write stop condition to i2c bus
+	i2c_write_timeout_us(PBDRV_I2C, addr, buf, sz, false, PB_TIMEOUT_US);
+
+	i2c_set_slave_mode(PBDRV_I2C, true, PBDRV_MOD_ADDR);
+}
+