diff --git a/src/app/prototest/Makefile.inc b/src/app/prototest/Makefile.inc
index d501de1139c24ab9c92f2a86ee92f1272c707294..56410e041761de8e011746c1e56596f8cc6070b6 100644
--- a/src/app/prototest/Makefile.inc
+++ b/src/app/prototest/Makefile.inc
@@ -1,3 +1,2 @@
 loop ?= 1
-
-TARGETS += src/lib/ubjson/ubjr.c src/lib/ubjson/ubjw.c
+TARGETS += src/os/object/xdrstream.cc
diff --git a/src/app/prototest/main.cc b/src/app/prototest/main.cc
index c7d0838df05002d6052c81ba0e298f4e091e5a53..8613bea4af2c410f0fea77824f60b7a12097acf2 100644
--- a/src/app/prototest/main.cc
+++ b/src/app/prototest/main.cc
@@ -2,6 +2,11 @@
 #include "driver/gpio.h"
 #include "driver/stdout.h"
 #include "lib/ArduinoJson.h"
+#include "lib/modernjson/json.h"
+#include "object/stdbuf.h"
+#include "object/xdrstream.h"
+
+char buf[128];
 
 void loop(void)
 {
@@ -10,6 +15,30 @@ void loop(void)
 	ArduinoJson::JsonObject& root = jsonBuffer.parseObject(json);
 	const char *sensor = root["sensor"];
 	kout << "sensor: " << sensor << endl;
+
+	nlohmann::json j = R"({"compact": true, "schema": 0})"_json;
+	std::vector<std::uint8_t> v_cbor = nlohmann::json::to_cbor(j);
+
+	kout << "CBOR vector is " << hex;
+	for (unsigned int i = 0; i < v_cbor.size(); i++) {
+		kout << v_cbor[i] << " ";
+	}
+	kout << endl;
+
+	kout << "manual JSON: {\"sensor\":\"gps\",\"time\":" << dec << 1351824120;
+	kout << ",\"data\":[" << 48.756080 << "," << 2.302038 << "]}" << endl;
+
+	BufferOutput<XDRStream> foostream(buf);
+
+	foostream << 123 << 0 << 12345678;
+
+	kout << "foostream is " << hex;
+	for (unsigned int i = 0; i < 32; i += 4) {
+		kout << (unsigned char)buf[i] << (unsigned char)buf[i+1];
+		kout << (unsigned char)buf[i+2] << (unsigned char)buf[i+3] << " ";
+	}
+	kout << endl;
+
 	gpio.led_toggle(1);
 #ifdef TIMER_S
 	kout << dec << uptime.get_s() << endl;