diff --git a/fpga_spn/raven_spn b/fpga_spn/raven_spn
index 25dcaf1..1f1f998 100755
Binary files a/fpga_spn/raven_spn and b/fpga_spn/raven_spn differ
diff --git a/fpga_spn/src/raven_spn.cpp b/fpga_spn/src/raven_spn.cpp
index 2fc58a7..a3756da 100644
--- a/fpga_spn/src/raven_spn.cpp
+++ b/fpga_spn/src/raven_spn.cpp
@@ -68,6 +68,17 @@ int main() {
 
 
 
+    uint32_t step = 100000;
+    uint32_t iterations = 10;
+
+
+
+    int in_addr   = 0x30000000; // place input samples in the SPI memory
+    int out_addr  = 0x3C000000;
+    int out_addr2 = 0x3E000000;
+
+
+
     spn::mode_reg() = 1;
     spn::start_reg() = 1;
     wait_for_spn_interrupt();
@@ -91,29 +102,39 @@ int main() {
 
     printf("Result Bytes: %d\n", result_bytes);
 
-    uint32_t step = 50000;
-    uint32_t iterations = 2;
+    uint32_t in_bytes = step * sample_bytes;
+    uint32_t out_bytes = step * result_bytes;
+
+    uint32_t total_in = in_bytes * iterations;
+
+    if (total_in > (out_addr - in_addr)) {
+        printf("ERROR: input data requires %d bytes, only %d bytes available\n", total_in, out_addr - in_addr);
+        return 1;
+    }
+    if (out_bytes > (out_addr2 - out_addr)) {
+        printf("ERROR: output data requires %d bytes, only %d bytes available\n", out_bytes, out_addr2 - out_addr);
+        return 1;
+    }
 
     
-    uint32_t in_beats = (step * sample_bytes) / axi_bytes;
+    uint32_t in_beats = in_bytes / axi_bytes;
     if (in_beats * axi_bytes < step * sample_bytes) in_beats++;
-    uint32_t out_beats = (step * result_bytes) / axi_bytes;
+    uint32_t out_beats = out_bytes / axi_bytes;
     if (out_beats * axi_bytes < step * result_bytes) out_beats++;
 
-	int in_addr  = 0x20010000; // place input samples in the SPI memory
-    int out_addr = 0x20210000;
+    uint32_t current_in_addr = in_addr;
     int fpga_address_in = fpga_alloc(step * sample_bytes + 64);
     int fpga_address_out = fpga_alloc(step * result_bytes + 64);
 
     // inject SPN input data
-    spn_checker::input_addr_reg() = in_addr;
+    spn_checker::input_addr_reg() = current_in_addr;
     spn_checker::num_input_samples_reg() = sample_bytes * step * iterations;
     spn_checker::start_data_trans_reg() = 1;
     spn_checker::output_addr_reg() = out_addr;
 
     //run_xspn(in_addr, out_addr);
     for (int k = 0; k < iterations*step; k+=step) {
-        fpga_dma(1, fpga_address_in, in_addr, step * sample_bytes);
+        fpga_dma(1, fpga_address_in, current_in_addr, step * sample_bytes);
         run_xspn(fpga_address_in, fpga_address_out, step, in_beats, out_beats);
         wait_for_spn_interrupt();
         spn::interrupt_reg() = 1;
@@ -123,7 +144,7 @@ int main() {
         spn_checker::length_reg() = step;
         spn_checker::start_result_check_reg() = 1;
 
-		in_addr += step * sample_bytes; // 5 bytes in each sample
+		current_in_addr += step * sample_bytes; // 5 bytes in each sample
 	}
 
     fpga_free(fpga_address_in);