@@ 47,6 47,7 @@ 
 #include "arch/atmega48p_spi.h"
 #include "arch/atmega48p_timer1.h"
 #include "arch/atmega48p_timer2.h"
+#include "arch/atmega48p_usart.h"
 #elif defined(MCU_ATTINY13A)
 #include "arch/attiny13a.h"
 #else

          

@@ 0,0 1,57 @@ 
+/*
+ * Copyright (c) 2023-2024 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef AVR_COMMON_ARCH_ATMEGA48P_USART_H
+#define AVR_COMMON_ARCH_ATMEGA48P_USART_H
+
+#ifndef _ASM
+
+/* transmit a single byte */
+static inline void usart_tx_byte(uint8_t byte)
+{
+	/* wait for space is UDR */
+	while (!(mmregs->ucsr0a & REG_UCSRnA_UDRE))
+		;
+
+	/* send byte */
+	mmregs->udr0 = byte;
+}
+
+static inline void usart_tx_be16(uint16_t v)
+{
+	usart_tx_byte(v >> 8);
+	usart_tx_byte(v & 0xff);
+}
+
+static inline void usart_tx_flash_str(const __flash char *ptr)
+{
+	while (!*ptr) {
+		usart_tx_byte(*ptr);
+		ptr++;
+	}
+
+	usart_tx_byte('\n');
+}
+
+#endif
+
+#endif