diff --git a/firmware/ice40-riscv/icE1usb/misc.c b/firmware/ice40-riscv/icE1usb/misc.c
new file mode 100644
index 0000000..9ceb8c6
--- /dev/null
+++ b/firmware/ice40-riscv/icE1usb/misc.c
@@ -0,0 +1,50 @@
+/*
+ * misc.c
+ *
+ * Copyright (C) 2019-2020  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "config.h"
+#include "misc.h"
+
+
+struct misc {
+	uint32_t warmboot;
+	uint32_t gpio;
+	uint32_t e1_led;
+	uint32_t _rsvd;
+	struct {
+		uint16_t tx;
+		uint16_t rx;
+	} e1_tick[2];
+	uint32_t gps;
+	uint32_t time;
+	uint32_t pdm[8];
+} __attribute__((packed,aligned(4)));
+
+static volatile struct misc * const misc_regs = (void*)(MISC_BASE);
+
+
+static const int pdm_bits[5] = { 12, 12, 8, 8, 8 };
+
+
+void
+pdm_set(int chan, bool enable, unsigned value, bool normalize)
+{
+	if (normalize)
+		value >>= (16 - pdm_bits[chan]);
+	if (enable)
+		value |= 0x80000000;
+	misc_regs->pdm[chan] = value;
+}
+
+
+uint16_t
+e1_tick_read(void)
+{
+	return misc_regs->e1_tick[0].tx;
+}