diff --git a/firmware/hsdaoh/hsdaoh_nano20k_misrc/top.v b/firmware/hsdaoh/hsdaoh_nano20k_misrc/top.v
index 9e992a6..73d176b 100644
--- a/firmware/hsdaoh/hsdaoh_nano20k_misrc/top.v
+++ b/firmware/hsdaoh/hsdaoh_nano20k_misrc/top.v
@@ -10,8 +10,8 @@ module top (
 	tmds_d_n,
 	tmds_d_p,
 	adc0_data,
-    adc1_data,
-    gpio_data,
+	adc1_data,
+	gpio_data,
 	adc_clk,
 	uart_rx,
 	uart_tx,
@@ -27,8 +27,8 @@ module top (
 	output wire [2:0] tmds_d_p;
 
 	input wire [11:0] adc0_data;
-    input wire [11:0] adc1_data;
-    input wire [7:0] gpio_data;
+	input wire [11:0] adc1_data;
+	input wire [7:0] gpio_data;
 
 
 	input wire uart_rx;
@@ -45,10 +45,14 @@ module top (
 
 	// assign adc_clkout = clk_data_pll0_ext;
 
+	// with FBDIV = 52 (maximum)
 	// 477 MHz, maximum that works with the nano 20K
 	// 477/5 = 95.4 MHz
+	// with FBDIV = 47 (enough for 32 bit at 40 MHz)
+	// 432 MHz
+	// 432/5 = 86.4 MHz
 	localparam HDMI_PLL_IDIV  = 2;
-	localparam HDMI_PLL_FBDIV = 52;
+	localparam HDMI_PLL_FBDIV = 47;
 	localparam HDMI_PLL_ODIV  = 2;
 
 	// PLL for HDMI clock
@@ -92,7 +96,7 @@ module top (
 	reg [31:0] fifo_in;
 
 	wire write_enable;
-    wire dword_enable;
+	wire dword_enable;
 
 	wire [31:0] fifo_out;
 	wire fifo_empty;
@@ -105,7 +109,7 @@ module top (
 
 	wire [31:0] settings;
 
-    assign dword_enable = settings[19];
+	assign dword_enable = settings[19];
 
 	async_fifo #(
 		.DSIZE(32),
diff --git a/misrc_tools/cthreads.h b/misrc_tools/cthreads.h
new file mode 100644
index 0000000..11a26fa
--- /dev/null
+++ b/misrc_tools/cthreads.h
@@ -0,0 +1,10 @@
+#include <pthread.h>
+
+typedef pthread_t thrd_t;
+typedef int (*thrd_start_t) (void*);
+
+#define thrd_success 0
+
+#define thrd_create(a,b,c) pthread_create(a,NULL,b,c)
+#define thrd_join(a,b) pthread_join(a,b)
+#define thrd_sleep(a,b) nanosleep(a,b)
\ No newline at end of file
diff --git a/misrc_tools/extract.asm b/misrc_tools/extract.asm
index c59b92b..952583f 100644
--- a/misrc_tools/extract.asm
+++ b/misrc_tools/extract.asm
@@ -52,7 +52,9 @@ default rel
 	%endif
 %endmacro
 
-section .note.GNU-stack noalloc noexec nowrite progbits
+%ifidn __OUTPUT_FORMAT__,elf64
+	section .note.GNU-stack noalloc noexec nowrite progbits
+%endif
 
 section .data
 	ALIGN 16
diff --git a/misrc_tools/misrc_capture.c b/misrc_tools/misrc_capture.c
index 1be1116..3c7ad3f 100644
--- a/misrc_tools/misrc_capture.c
+++ b/misrc_tools/misrc_capture.c
@@ -29,7 +29,11 @@
 #include <math.h>
 #include <stdint.h>
 #include <stdbool.h>
+#if __STDC_NO_THREADS__
+#include "cthreads.h"
+#else
 #include <threads.h>
+#endif
 #include <time.h>
 
 #ifndef _WIN32
@@ -335,7 +339,7 @@ int main(int argc, char **argv)
 			break;
 #endif
 		case 'x':
-			output_names[2] = optarg;
+			output_name_aux = optarg;
 			break;
 		case 'r':
 			output_name_raw = optarg;
diff --git a/misrc_tools/ringbuffer.c b/misrc_tools/ringbuffer.c
index 4c20c97..7ec9fee 100644
--- a/misrc_tools/ringbuffer.c
+++ b/misrc_tools/ringbuffer.c
@@ -21,22 +21,14 @@
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#define _GNU_SOURCE
+#include "shm_anon.h"
 #include <string.h>
 #include <unistd.h>
-#include <linux/memfd.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 
 #include "ringbuffer.h"
 
-#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 27)
-#include <sys/syscall.h>
-
-static inline int memfd_create(const char *name, unsigned int flags) {
-	return syscall(__NR_memfd_create, name, flags);
-}
-#endif
 
 int rb_init(ringbuffer_t *rb, char *name, size_t size) {
 
diff --git a/misrc_tools/shm_anon.h b/misrc_tools/shm_anon.h
new file mode 100644
index 0000000..a699c6f
--- /dev/null
+++ b/misrc_tools/shm_anon.h
@@ -0,0 +1,104 @@
+// based on: https://github.com/lassik/shm_open_anon/
+
+// Copyright 2019 Lassi Kortela
+// SPDX-License-Identifier: ISC
+
+#ifdef __linux__
+#define _GNU_SOURCE
+#include <linux/memfd.h>
+#include <linux/unistd.h>
+#endif
+
+#include <sys/types.h>
+
+#include <sys/mman.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#undef IMPL_MEMFD
+#undef IMPL_POSIX
+#undef IMPL_SHM_ANON
+#undef IMPL_SHM_MKSTEMP
+#undef IMPL_UNLINK_OR_CLOSE
+
+#if defined(__linux__)
+#if __GLIBC__ < 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ < 27)
+#include <sys/syscall.h>
+static inline int memfd_create(const char *name, unsigned int flags) {
+	return syscall(__NR_memfd_create, name, flags);
+}
+#endif
+#elif defined(__FreeBSD__)
+#define memfd_create(a,b) shm_open(SHM_ANON,O_RDWR,0)
+#elif defined(__OpenBSD__)
+#define IMPL_SHM_MKSTEMP
+#else
+#define IMPL_POSIX
+#endif
+
+#if defined(IMPL_POSIX) || defined(IMPL_SHM_MKSTEMP)
+#define IMPL_UNLINK_OR_CLOSE
+#endif
+
+#ifdef IMPL_UNLINK_OR_CLOSE
+static int
+shm_unlink_or_close(const char *name, int fd)
+{
+	int save;
+
+	if (shm_unlink(name) == -1) {
+		save = errno;
+		close(fd);
+		errno = save;
+		return -1;
+	}
+	return fd;
+}
+#endif
+
+#ifdef IMPL_POSIX
+static int
+memfd_create(const char *_name, unsigned int flags)
+{
+	char name[16] = "/shm-";
+	struct timespec tv;
+	unsigned long r;
+	char *const limit = name + sizeof(name) - 1;
+	char *start;
+	char *fill;
+	int fd, tries;
+
+	*limit = 0;
+	start = name + strlen(name);
+	for (tries = 0; tries < 4; tries++) {
+		clock_gettime(CLOCK_REALTIME, &tv);
+		r = (unsigned long)tv.tv_sec + (unsigned long)tv.tv_nsec;
+		for (fill = start; fill < limit; r /= 8)
+			*fill++ = '0' + (r % 8);
+		fd = shm_open(
+		  name, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW, 0600);
+		if (fd != -1)
+			return shm_unlink_or_close(name, fd);
+		if (errno != EEXIST)
+			break;
+	}
+	return -1;
+}
+#endif
+
+#ifdef IMPL_SHM_MKSTEMP
+static int
+memfd_create(const char *_name, unsigned int flags)
+{
+	char name[16] = "/shm-XXXXXXXXXX";
+	int fd;
+
+	if ((fd = shm_mkstemp(name)) == -1)
+		return -1;
+	return shm_unlink_or_close(name, fd);
+}
+#endif