Projects – texelography

Nissan Sunny Rz1 Digital Cluster Adapter Schematics and CAD

2022-10-23
by Clemens

I would like to make the Nissan Sunny Rz1 Digital Cluster Adapter open-source and allow DIYers to build the project themselves.

To build the adapter yourself, you will need to:

Have the adapter PCB manufactured, solder all components, and program it
Setup the correct dataset and configuration for your Rz1
3D-print the wiring harness connector adapters
Have the PCBs that are part of the connector manufactured
Build the wiring harness

Build the Adapter ECU

First, you need to order the manufacturing of the PCB. You can download the schematics and layout file below.

AdapterPCB The schematics to build the PCB

It is probably best to directly order them from a company which directly does SMD assembly to reduce the effort.

The firmware that you need to flash can be found here: https://github.com/Danaozhong/Nissan-Sunny-B12-Rz1-Digital-Cluster-Conversion-ECU-Firmware

You will need to clone the repository, build the firmware, and flash it to the STM32 located on the PCB board.

After assembly and flashing, you should be able to see a command prompt via the UART.

Build the Adapter Harness

To build the adapter harness, you will need the following parts:

3D-printed connector cases for the female plugs to connect to your vehicle harness. You can download the CAD drawings and STL files below.
The printed PCBs that are installed inside the 3D-printed connector cases (in total, 4 PCBs are needed).
The cluster connector salvaged from a wrecked Nissan Sunny B12
TE Connectivity connector 175964-2 to connect to the adapter ECU
TE Connectivity connector 172021-2 to connect to the digital cluster
Lots of automotive grade cables, crimp equipment, soldering equipment
Firewall grommet 38mm diameter

The instructions on how to build the adapter harness can be found in the Excel document below.

Harness_Pinout Download

CADDrawingsConnector Download

ConnectorPCBs Download

Digital Cluster Conversion Kit Launch!

2021-03-112021-03-14
by Clemens

I am pleased to announce that for the Nissan Rz1 digital cluster conversion kit project, all development and testing steps are complete. The product will be launched in April 2021.

To put it simply, this kit allows you to put the JDM digital cluster into your US/European Nissan Rz1, without having to cut any cables or complex rewiring. No hard-to-find special speed sensor or fuel sensor are required.

JDM digital cluster: Not included in the kit

For DIY enthusiasts, all technical documents, PCB layouts, part lists and 3D printing components will be made available soon. The firmware of the conversion ECU is already open source.

It will contain the following parts:

The adapter harness plugs into factory wiring, and converts it to the digital cluster wiring

The Digital Cluster Conversion ECU converts the speed and fuel signals, so that the correct values are indicated.

A simple and easily-available electronic speed sensor is used to measure the vehicle speed. It replaces the older speedometer cable used for the analogue cluster.

As you can see from the pictures, it is a complete plug&play solution, which can be installed without having to cut connectors, or rewire your vehicle cable loom. The adapter can be fully removed; and the factory cluster reinstalled.

Basically, the only wiring step necessary is to connect battery supply, ground, and accessories.

The kit will only work on specific left-hand driven Nissan Rz1 models.

Building a Digital Cluster Converter

2020-02-122021-03-13
by Clemens

Today I would like to share some exciting news for you, and make it official – I am building a converter to allow you to fit a digital cluster into your eighties oldschool vintage car!

In the last few months, I published details on how the digital cluster in a Nissan Sunny B12 Rz-1 works, and how it is integrated into the vehicle electronics. Well knowing that even with the information available, most owners of these old cars would not be able to do the job themselves, I decided to start building an adapter.

So how’s the idea?

Having solved all the big questionmarks around the digital cluster was not sufficient. From knowing how the speed sensor signal looks like (0-5V PWM), or how the fuel sensor of the digital cluster works, to have a digital cluster successfully installed in your car, is a long way to go. That’s why I decided to build you guys a simple, plug-and-play conversion. The idea is that with my kit you just install a different speed sensor, attach my harness to the one already installed in the car, and connect it to your digital cluster. No hassle, no removal of the dashboard, no cutting of wires, no soldering.

The Rz1 digital cluster converter – the PCB of the ECU on the right, and the 3D printed plugs to hook up the adapter to your vehicle harness. The round thing in the upper right corner is the vehicle speed sensor, that fits the Rz1 gearbox.

The heart of the conversion is a little, custom made ECU based on an STM32 microcontroller. This chip will do the math, and adapt the signals that we provide to it to a format that the original Sunny Rz1 digital cluster will understand. It will basically work as a translator between the electrical signals of your car and the digital cluster.

That solution means that you don’t have to bother anymore to find a Nissan Rz1 JDM digital speed sensor or aquire a fuel level sensor from a model with a digital dash – if you own these parts, consider yourself lucky, as these are pretty much Unobtanium.

In more detail, the ECU will convert the vehicle speed signal from a sensor that fits mechanically onto the Rz1 transmission (see the black round thingy in the picture). It gives out 4 pulses per rotation – but the digital cluster needs 24 pulses per rotation! To solve this, the ECU is constantly monitoring the frequency of the vehicle speed sensor, and multiplies this frequency by 8 – and then gives this signal to the digital cluster.

For the fuel signal, the ECU does a similar job: A ADC (analog-digital-converter) measures the fuel quantity in your car, and uses a lookup table to calculate the fuel output level. Say for example, the analog fuel sensor measures 50Ohms, then the ECU knows that this corresponds to a fuel level of 30%. Using the lookup table of the digital cluster, it then translates this fuel level to a voltage: Say that 30% means a fuel signal of 2.1V, then the ECU will provide a 2.1V signal to the cluster, which will then display the correct fuel quantity of 30%.

Some geeky technical details — the STM32 has 256k flash and 64k RAM. The application uses a FreeRTOS operating system. Four different tasks manage the signal conversion, and a serial UART interface allows you to print debug information or change settings. The conversion factors and lookup tables are stored in a data flash.

But having an ECU to convert the signals is not enough, as it would still mean that you would have to spend hours and hours removing your vehicles’ dashboard, cluster, harness, cut wires, solder, measure… it can easily take several weeks to accomplish this. I asked myself, how is it possible to make the installation as easy as possible, so that basically everyone can do it?

The idea that popped into my mind was to build an adapter wire harness, which plugs into the OEM harness, and changes the pinout. On the other side of the adapter harness, you can directly connect your cluster. The biggest obstacle here is that the cluster connectors in the Rz1 are 30 years old, and there’s no place on earth were you can buy a matching female connector. I searched for days. You just can’t.

So that basically means that if you want to install a digital cluster, you have to cut off the original connectors, and solder everything together?

You don’t.

After giving up searching a suitable connector that plugs into the OEM harness, I decided to build my own. Above is the CAD drawing of it, and if you scroll all the way up to the picture, you can see the 3D printed result cases. Take two more custom-made electrical PCB circuits and a strain relief, and voilà – your custom made electrical connector is completed!

The custom made PCB will serve as the electrical connection. The cables are soldered to the PCB, and then slid into the 3D printed case, where they are secured. The connector can directly connect to the Rz1 harness, without any cutting required! Compare the gray plug cases with the electrical connector that came from a junkyard Sunny B12 – they will perfectly lign up.

The adapter is now in the late stages of development. The custom plugs are made, the PCB layout for the ECU is done, the software is about 80% complete, next up follows making a prototype and a test installation in a Nissan Rz1. After extensive testing, I hope I can offer you this adapter for sale within one or two month.

What will it cost?

Considering the effort that it took to write the code, design PCBs, the costs for custom PCBs and 3D printing, doing all the research on the Rz1 digital wire harness, measuring out a complete Rz1 harness from Russia, and trying out a lot of different approaches, development of this adapter had cost me a lot. The fact that the number of potential buyers will certainly be less than ten, will not help me a lot either. I am targeting a sales price of roughly 450€ per complete converter, including speed sensor, adapter harness, and custom made ECU. If you are on a tight budget, all the schematics and drawings will be published after the project was completed, so that you can also build everything yourself.

That being said, thank you for reading and the interest! Have fun keeping your old cars on the road, and make sure to come back regularly to find out about updates on this project!

By the way, for all the software guys and girls among you, feel free to check out my GitHub, you will find the complete source code for the adapter there. I will probably do another blog post which focusses only on the software parts, so stay tuned!

Nissan Sunny B12 Rz-1 Digital Speed Sensor

2019-11-28
by Clemens

Today I finally managed to measure the signals on the digital speed sensor. I don’t own any of the Rz-1 digital cluster parts, but luckily, a friend borrowed me his sensor and allowed me to reverse-engineer it.

The speed sensor has a connector with three pins: black (right), yellow (middle), red (left).

Based on what I measured, black is GND, red is +5V supply, and yellow is the speedometer signal. The based on my scope prints, it seems that per revolution of the speedo cable we can see 24 pulses:

When I rotate the pin of the speed sensor at about one revolution per two seconds, the cluster shows me – very roughly – 13 km/h.

When only connecting the +5V and GND, but leaving the signal pin open. the signal looks idential. When rotating the pin of the sensor, the 5V pulses on the signal line are still visible.

Therefore, it seems we can just use a 0-5V PWM, and bring it onto the cluster, and it should display the speed signal.

Nissan Rz1 Digital Cluster Conversion

2019-06-212019-11-20
by Clemens

A few years ago, I modified a LHD Nissan Sunny B12 Coupé Rz1 and fitted a RHD JDM digital clusters, and uploaded a short video of it on youtube.

I received a lot of questions on this modification, and decided to publish the knowledge I gained here.
Most importantly, here is the pinout.

Pinout Comparison of the RHD JDM loom and the LHD EUDM/USDM loom

Connector Pinout

The connectors are drawn on the left side. Basically, you see five connectors here. Connector “A”, “B”, and “C” under the header “Digitaltachostecker” describe the connector of the digital cluster. Connector “A” is the large one that powers the talltales and warning lights, connector “B” is the hard-to-find black one, that provides all the actual digital signals. The three-pin connector “C” can not be found on the cluster, but is the connector on the tachometer sensor in the engine bay (you need that part too).

The connectors labeled with “EU stecker” refer to the ones that you will find in your LHD Rz1s that came with analog clusters. You should most likely find them in your car if you remove the cluster.

In case you have a low-end spec B12 that came without a rpm gauge (some U.S. Sentras maybe?), your connector layout is probably different again.

The drawings show the connectors (sockets) on the cluster, as if you look on the backside of the cluster. They do not show the connectors on the harness!

The first problem you’ll face is that you need to get the small connector “B”, which, if it is not attached to your digital cluster, is pretty much unobtanium. You could try to find the original part number or a the part number from the supplier who made this connector, or in the worst case, replace the connector with a diffent type of similar size / pin cont and just solder everything together.
The white, larger connector “A” is physically identical to connector “A” of your LHD harness, but with a different pinout.

You got your hands on some plugs? Good, then you can already solder everything together, and your digital cluster should already party come to life. PRM, turn indicators, telltales (except exhaust temperature), temperatur gauge and fuel should come to life.

Vehicle Speed Sensor

The next difficult task it to get a speed sensor. The analog clusters uses a mechanical speedo cable that connects the gearbox to the speedo pointer – that is 100% mechanical oldschoolness!

For the digital cluster, NISSAN chose to go half they way – they still use a mechanical cable, about 50 cm long, that connects the gearbox to an electrical sensor. That sensor converts the motion into PWM signals, that are electrically supplied to the cluster. For the conversion, you will need both the cable and the sensor. If you don’t have these parts, then the installation will be a bit more difficult. They will plug&play fit to any gearbox.
The digital sensor is connected with two cables, C2 and C3, to the main plug of the cluster. So you will need to add two wires from your engine bay to your cluster.

If I remember correctly, the speedo singal is triggered twice per revolution. If you don’t have a sensor, you might want to use a function generator and try to get your cluster displaying something. If you are struggling here, feel free to leave a comment, then I will look up the technical details.

From the youtube comments on my channel, I understood that there seem to be different types of sensors, depending on which engine / gearbox your donor car had. It is likely that non-matching gearboxes will provide false readings on the speedo! If this is the case, then you would need to invest more engineering into the problem, e.g. use a small microcontroller to correct the signal.

I once tried to fit a digital sensor from the B13/N14 series into an E16i gearbox, but they wouldn’t fix plug&play. The main problem was that while the diameter was the same, the axis of the sensor was slightly offset. With some fiddling you might be able to mount them, though.
These sensors might fit for the GA16i gearbox, though. If you tried going this way, please leave a comment and share your experiences! it would definitely be cleaner looking than the OEM B12 parts.

You will have to figure out a solution to mount the speedo sensor in your engine bay, as the LHD / RHD firewalls are different. I suggest to use a little metal plate to mount the sensor to, and then adapt that to the firewall.

Incorrect mounting with too much tension on the cable might lead to the speedo not working at all, faster wear-out or not working at all.

Fuel Level Sensor

A problem which is not yet solved, it the fuel gauge. The fuel sensors used in the JDM digital cluster cars have a different characteristic.

The analog clusters use an 8V voltage regulator, which is connected to the fuel gauge and the fuel sensor in series. The resistor value of the LHD fuel sensor is as follows:

Resistor Value [Ohm]	Displayed Fuel Level
2,4	110%
11,8	100% (full)
21	77%
35,7	48%
61,8	25%
80,6	5%
87	-1%

The digital cluster characteristic is quite different. I used a JDM cluster and measured the fuel input. The fuel sensor is supplied by 5V, and depending on the resistor values, the following fuel level is displayed:

Resistor Value [Ohm]	Number of bars
14,9	14 (full)
20,4	14 (full)
23,6	13
30,6	13
78	10
105	8
216	6
300	4
400	3
600	2
717	1
809	1
1000	0 (empty)

With this information, you should be able to build your own adapter for the fuel sensor.

Propeller Clock

2019-01-072019-01-16
by Clemens

This project started in 2010 as a university project with the goal do develop a rotation clock. Main objectives of the project was to develop an induction power supply using a MOSFET H bridge and and to layout a PCB. The PCB contains a 8051 microcontroller and ten OSRAM RGB LEDs as well as an optical reflex coupler. The board is mounted on a rotateable motor, which propels the board to 40 rotations per second. Based on the input data of the reflex coupler, the microcontroller then calculates the current position and switches the LEDs on or off so that the user sees a stable image.

The PCB features a power supply that suported AC/DC inputs, ranging from 7 to 20V, while delivering a stable 5V DC current used to power the 8051 microcontroller soldered onto the PCB. The board is powered using induction. A MOSFET H bridge is used to power the primary coil, while the secondary coil is mounted on the rotateable part. Programming started in Assembler (requirement of university), but will be finished in C. The project is not yet completed – the PCB works as expected and the induction power supply is working, but the current mechanical setup is not fast enough to create a stable image. Development is still ongoing (only problem is time 🙂 ).