Fork

Power test SDRAM

Assemble test stand for checking power consumption of SDRAM in different operating modes.

1. Structure. Connection diagram.

Today wireless devises are everywhere. They always need a battery power, so the problem of power consumption measurement during device development is very important. And this is what we needed to do also. For this purpose we've assembled a consumption testing stand. Flexibility that has Fork allows us to use it also at Quality control (QC) during production. Generally the stand can measure consumption of different devices, but for this article we'll measure only some operating modes.

For measurements we've chisen this modes of device with SDRAM

stand-by
read
write
power-down

For stand we need

Fork
Accurate shunt 0.47 Om
device with SDRAM
some wires

Circuit diagram of stand:

Breaking the power supply we put a shunt resistor if small Om resistance, this is where we'll measure consumption according to voltage drop using Fork differential input. We should be careful as maximum input voltage is +-1V.

Photo of testing stand, but sorry the testing device is hidden I can't show it for now.

Here is a set of shunt resistors

2. Control via Python script

For getting data we will use Fork Stream ability. It'll be easy to convert Fork data directly to measurements. For this we can use function


Fork.startStreamBlocking([0],
stream_callback,
reply_format=Fork.RAW_ADC,
data_rate=data_rate)

First parameter is for set of AI channels for reading, then your callback function that is called after a packet received, then data format and data rate of sampling.
The most important for us is a callback function. Data is received as raw ADC data. After receving some packets we can convert them to power consumption measurements. For convenience we'll make it in two steps. Firstly convert raw data to voltage on input


V = ADC/4095*2.2-1.1

where V is voltage on shunt resistor, ADC – raw ADC data.
Then voltage to current


I = V/Rshunt

where R is Om of shunt resistor

Now we've started measurements and changed modes by hands.

Here we see write(1) into SDRAM and read(2) from SDRAM. With 180 mA, and 156 mA.

Here we see switching of SDRAM from stand-by to power-down.

So we have such table.

Thanks to Fork we've got a very good and simple stand for measuring different devices power consumption in different modes.

3. References to the code examples

Python

Functional test fixtured based on Fork

When the board comes out of the assembly line at the factory, it must be tested. We do this using a Fork that connects the board with needles. Here is a real stand of a real NOTA device.

How the Fork saved 500 devices

In this article, we will talk about how we saved devices from being thrown into the trash with the help of a test fixture on the Fork

Expand the capabilities of the RPi with the help of a Fork

We say: expand the capabilities of the RPi with the help of a Fork, because Fork is not a competitor to RaspberryPi, but a companion.

Measuring temperature and humidity

In this article, we will look at getting temperature and humidity readings using a Fork, which will be used in an automated test fixture.

Hardware tests automation with Fork

Pytest is a modern test tool with a wide infrastructure

Automated investigation of the transistor with a Fork

In this material we checked the input and output characteristics of the 2h3904 bipolar transistor

Power test the STM32F0 debugging Board

Often there is a problem of functional testing of the device at different values of the supply voltage. Fork helps you automate the testing process.

Testing the Chinese relay using Fork and Python

In this article, we will use the Fork to examine the Chinese relay for reliability (number of switches).

Temperature control of the w5500 chip using a Fork

In this material, we will create a Fork stand that will automatically monitor the temperature of individual circuit elements.

Power test SDRAM on Fork

In this material, we have assembled a testbed on the Fork to check the power consumption of SDRAM in various operating modes.