diff --git a/software/src/creole_interface.c b/software/src/creole_interface.c
new file mode 100644
index 0000000..4d276c3
--- /dev/null
+++ b/software/src/creole_interface.c
@@ -0,0 +1,128 @@
+#include <sys_clock.h>
+#include "control_loop_cmds.h"
+#include "creole.h"
+#include "creole_upsilon.h"
+#include "pin_io.h"
+
+static inline uint32_t
+sign_extend(uint32_t in, unsigned len)
+{
+	if (in >> (len - 1) & 1) {
+		uint32_t mask = (1 << len) - 1;
+		return ~mask | (in & mask);
+	} else {
+		return in;
+	}
+}
+
+creole_word
+upsilon_get_adc(creole_word adc)
+{
+	if (adc < 0 || adc >= ADC_MAX)
+		return 0;
+
+	*adc_arm[adc] = 1;
+	/* TODO: sleep 550 ns */
+	while (!*adc_finished[adc]);
+
+	creole_word w = sign_extend(*from_adc[adc]);
+	*adc_arm[adc] = 0;
+
+	return w;
+}
+
+static uint32_t
+send_dac(creole_word dac, uint32_t val)
+{
+	*to_dac[dac] = val;
+	*dac_arm[dac] = 1;
+	/* TODO: sleep */
+	while (!*dac_finished[dac]);
+	uint32_t w = sign_extend(*from_dac[dac], 20);
+	*dac_arm[dac] = 0;
+
+	return w;
+}
+
+creole_word
+upsilon_get_dac(creole_word dac)
+{
+	if (dac < 0 || dac >= DAC_MAX)
+		return 0;
+
+	send_dac(dac, 0x1 << 23 | 0x1 << 20);
+	return send_dac(dac, 0);
+}
+
+creole_word
+upsilon_write_dac(creole_word dac, creole_word val)
+{
+	if (dac < 0 || dac >= DAC_MAX)
+		return 0;
+	send_dac(dac, 0x1 << 20 | val);
+	return 1;
+}
+
+creole_word
+upsilon_usec(creole_word usec)
+{
+	k_sleep(K_USEC(usec));
+	return 0;
+}
+
+creole_word
+upsilon_control_loop_read(creole_word *high_reg,
+                          creole_word *low_reg,
+                          creole_word code)
+{
+	*cl_cmd = code;
+	*cl_start_cmd = 1;
+	while (!*cl_finish_cmd);
+	*high_reg = cl_word_out[0];
+	*low_reg = cl_word_out[1];
+	*cl_start_cmd = 0;
+
+	return 0;
+}
+
+creole_word
+upsilon_control_loop_write(creole_word high_val,
+                           creole_word low_val,
+                           creole_word code)
+{
+	*cl_cmd = CONTROL_LOOP_WRITE_BIT | code;
+	cl_word_in[0] = high_val;
+	cl_word_in[1] = low_val;
+	*cl_start_cmd = 1;
+	while (!*cl_finish_cmd);
+	*cl_start_cmd = 0;
+
+	return 0;
+}
+
+creole_word
+upsilon_load_waveform(struct creole_env *env, creole_word slot,
+                      creole_word db)
+{
+	/* TODO */
+	return 0;
+}
+creole_word
+upsilon_exec_waveform(creole_word slot, creole_word dac)
+{
+	/* TODO */
+	return 0;
+}
+creole_word
+upsilon_sendval(creole_word num)
+{
+	/* TODO */
+	return 0;
+}
+
+creole_word
+upsilon_senddat(struct creole_env *env, creole_word db)
+{
+	/* TODO */
+	return 0;
+}