diff --git a/bin/checksum_test.py b/bin/checksum_test.py
new file mode 100644
index 0000000..622c4ee
--- /dev/null
+++ b/bin/checksum_test.py
@@ -0,0 +1,37 @@
+#!/usr/bin/python3
+
+from scapy.all import *
+
+if __name__ == '__main__':
+    p = []
+
+    e0 = Ether(src="00:00:00:00:00:00",
+               dst="00:00:00:00:00:00")
+
+    e = Ether(src="02:53:55:42:45:01",
+              dst='ff:ff:ff:ff:ff:ff')
+
+    i0 = IP(src = "0.0.0.0",
+            dst = "0.0.0.0")
+
+    i4 = IP(src = "192.168.1.1",
+            dst = "192.168.4.2")
+
+    i6 = IPv6(src = "2001:db8:42::1",
+             dst = "2001:db8::2")
+
+    t0 = TCP(dport=0, sport=0)
+    t = TCP(dport=80, sport=random.randint(49152,65535))
+
+    d0 = ""
+    d = "A"
+
+    p.append(e0 / i0 / t0 / d0)
+    p.append(e / i4 / t / d)
+#    p.append(e / i6 / t / d)
+
+    for test in p:
+        print("p = {}".format(test.__repr__())!)
+        packet_raw = str(test)
+        checksum_scapy = IP(packet_raw)[TCP].chksum
+        print("chk = {}".format(checksum_scapy))
diff --git a/doc/plan.org b/doc/plan.org
index 5b0e3c3..4a93546 100644
--- a/doc/plan.org
+++ b/doc/plan.org
@@ -4602,6 +4602,92 @@ Likely requires "Installation of Digilent Adept Tools"
 
 (website does not load as of 2019-06-17, 10:39)!
 
+Install deb that supports the hardware test:
+
+#+BEGIN_CENTER
+10-ipv6-privacy.conf  Desktop  digilent.adept.runtime_2.19.2-amd64.deb
+root@rainbow16:~# dpkg -i digilent.adept.runtime_2.19.2-amd64.deb
+Selecting previously unselected package digilent.adept.runtime.
+(Reading database ... 275077 files and directories currently installed.)
+Preparing to unpack digilent.adept.runtime_2.19.2-amd64.deb ...
+Unpacking digilent.adept.runtime (2.19.2) ...
+Setting up digilent.adept.runtime (2.19.2) ...
+Processing triggers for libc-bin (2.23-0ubuntu11) ...
+root@rainbow16:~#
+
+#+END_CENTER
+
+The required tool does not seem to be included in the adept runtime:
+
+#+BEGIN_CENTER
+root@rainbow16:~# dpkg -l | grep digilent
+ii  digilent.adept.runtime                     2.19.2                                       amd64        Digilent Adept Runtime
+root@rainbow16:~# dpkg -L digilent.adept.runtime  | grep djtgcfg
+root@rainbow16:~#
+
+#+END_CENTER
+
+Trying -tools as well
+
+#+BEGIN_CENTER
+[12:55] line:Downloads% scp digilent.adept.utilities_2.2.1-amd64.deb root@rainbow16.place6.ungleich.ch:
+digilent.adept.utilities_2.2.1-amd64.deb                                                     100%  465KB   1.2MB/s   00:00
+[12:56] line:Downloads%
+
+root@rainbow16:~# ls
+10-ipv6-privacy.conf  Desktop  digilent.adept.runtime_2.19.2-amd64.deb  digilent.adept.utilities_2.2.1-amd64.deb
+root@rainbow16:~# dpkg -i digilent.adept.utilities_2.2.1-amd64.deb
+Selecting previously unselected package digilent.adept.utilities.
+(Reading database ... 275201 files and directories currently installed.)
+Preparing to unpack digilent.adept.utilities_2.2.1-amd64.deb ...
+Unpacking digilent.adept.utilities (2.2.1) ...
+Setting up digilent.adept.utilities (2.2.1) ...
+Processing triggers for man-db (2.7.5-1) ...
+root@rainbow16:~# which  djtgcfg
+/usr/bin/djtgcfg
+root@rainbow16:~#
+
+#+END_CENTER
+
+New error from the hardware test:
+
+#+BEGIN_CENTER
+
+---------------------------------------------
+[pcie]: Running Auto Test
+---------------------------------------------
+Traceback (most recent call last):
+  File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_core.py", line 16765, in <lambda>
+    lambda event: event.callable(*event.args, **event.kw) )
+  File "sw/host/script/NfSumeTest.py", line 848, in UpdateProgress
+    self.progressDlg.Update(self.curProgress, str(localLine))
+  File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_core.py", line 16710, in __getattr__
+    raise PyDeadObjectError(self.attrStr % self._name)
+wx._core.PyDeadObjectError: The C++ part of the NfSumeProgress object has been deleted, attribute access no longer allowed.
+Exception in thread Thread-21:
+Traceback (most recent call last):
+  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
+    self.run()
+  File "sw/host/script/NfSumeTest.py", line 947, in run
+    self.target(*self.data)
+  File "sw/host/script/NfSumeTest.py", line 466, in TestInterface
+    self.serialCon.readlines()
+  File "/usr/lib/python2.7/dist-packages/serial/serialposix.py", line 495, in read
+    raise SerialException('device reports readiness to read but returned no data (device disconnected or multiple access on port?)')
+SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
+
+
+
+#+END_CENTER
+
+*** 2019-06-17: checksum delta / diff approach
+**** crc / checksum operation
+"The checksum field is the 16 bit one's complement of the one's
+complement sum of all 16-bit words in the header and text."
+https://en.wikipedia.org/wiki/Transmission_Control_Protocol#Checksum_computation
+
+
+
 ** References / Follow up
 *** RFC 791 IPv4 https://tools.ietf.org/html/rfc791
 *** RFC 792 ICMP https://tools.ietf.org/html/rfc792
diff --git a/netpfga/hardware-test-20190617.png b/netpfga/hardware-test-20190617.png
new file mode 100644
index 0000000..7913cc8
Binary files /dev/null and b/netpfga/hardware-test-20190617.png differ