--- /dev/null
+/*
+ * Copyright © 2023 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#ifndef _AO_ARCH_H_
+#define _AO_ARCH_H_
+
+#include <stm32f1.h>
+
+#ifndef AO_STACK_SIZE
+#define AO_STACK_SIZE 512
+#endif
+
+#define AO_PORT_TYPE uint16_t
+
+#define ao_arch_naked_declare __attribute__((naked))
+#define ao_arch_naked_define
+#define __interrupt(n)
+#define __at(n)
+
+#define ao_arch_nop() asm("nop")
+
+#define ao_arch_interrupt(n) /* nothing */
+
+#define AO_ROMCONFIG_SYMBOL __attribute__((section(".init.1"))) const
+#define AO_USBCONFIG_SYMBOL __attribute__((section(".init.2"))) const
+
+#define AO_SYSTICK (AO_HCLK / 8)
+
+#if AO_NONMASK_INTERRUPT
+#define AO_STM_NVIC_NONMASK_PRIORITY 0x00
+
+/* Set the basepri register to this value to mask all
+ * non-maskable priorities
+ */
+#define AO_STM_NVIC_BASEPRI_MASK 0x10
+#endif
+
+#define AO_STM_NVIC_HIGH_PRIORITY 0x40
+#define AO_STM_NVIC_MED_PRIORITY 0x80
+#define AO_STM_NVIC_LOW_PRIORITY 0xC0
+#define AO_STM_NVIC_CLOCK_PRIORITY 0xf0
+
+#endif /* _AO_ARCH_H_ */