M24xxx Series – Cheap Memory for Microcontrollers

MicroCrystal RV-8803 – A Really Accurate RTC June 17, 2019- RTC chips traditionally were the domain of Maxim and NXP. Switzerland-based MicroCrystal recently made quite a buzz with its RV-8803, which offers simple integration, an I2C interface and extreme accuracy. Let us start out by looking at a system overview. Figure one shows how this I2C RTC is made up internally – interested observers note […]
Analog Devices’ LTM2887 – If a Digital Bus Needs Galvanic Isolation June 15, 2019- In theory, digital buses are intended to connect things to one another. Sadly, one sometimes wants but a logical connection – in many cases, galvanic isolation helps out. Should you ever feel like isolating very fast buses, definitely give the LTM2887 a chance. From a technical point of view, Linear Technologies attempt at entering the […]
AVAGO APDS-9008 or APDS-9005-020 – Keeping an Eye on Ambient Light June 14, 2019- Recent times saw quite a bit of interest for part numbers such as the APDS-9008 or APDS-9005-020 – they are a very interesting type of ambient light sensor. One of the oldest questions in regards to light sensors involves their spectral sensitivity. If a part is to output but one voltage level, the conversion between […]
STMicroelectronics’ LIS2DH12 – Low Power Motion Sensing June 12, 2019- Apple’s iPhone introduced gyroscopic sensors to a wider range – before that, accelerometers were not commonly found in consumer hardware. STM sells excellent parts which, however, get little media attention – time to take a look at the LIS2DH12. Integrating the part into your circuit as an MPU6500 alternative or MPU9500 alternative is not difficult. […]
Panasonic AMG8833 – FLIR for cheap June 7, 2019- FLIR made infrared thermal sensors cool – sadly, their parts are all but cheap (and suffer from export control problems). Panasonic’s Grid-EYE family is a low-resolution alternative which comes at significantly lower cost. From a technical point of view, Panasonic’s image sensor could not be simpler. We are looking at an 8×8 sensor with an […]
DipTronics DTS-62R-V – Small Switch, Very Big (and Very Cheap) June 5, 2019- When yours truly was but a lowly cadet, various US manufacturers produced (pricey but quite reliable) switches. Chinese vendors recently started to catch up – seeing the DTS-62R-V top our customer interest list shows that the run stage of the crawl-walk-run cycle is reached. DipTronics has been around the Asian switch market for ages, exhibiting […]

Cheap memory for microcontrollers

No matter how large your microcontroller’s memory might be – in practice, you will always need just a little bit more. In that case, STMicroelectronics’s SPI EEPROM provides a nice alternative to more established players.

Obviously, the biggest advantage of SPI involves the simplicity in connecting the part – you don’t need to worry about limited I2C address ranges or other problems. If your application has a free SPI controller, you are ready to go.



…if multiple CS pins are available, adding SPI EEPROMs becomes really simple

Alternatively, an SPI MUX can be driven from the GPIO port bank in a fashion similar to the bank switching implemented in Solomon Systech’s display controllers. Either way, the maximum permitted clock frequency is set at relatively speedy 5MhZ. STM simplifies the design of such boxes by providing a dedicated hold output input. If hold is activated, the serial data output line becomes high independence, while inputs and clock inputs are discarded silently.

A question of complications

ST‘s part differs from its colleagues in that it’s memory is organized in a set of banks. The total amount of spacious 2Mbit is divided into a groups of pages made up of 256 bytes each, one of which can be designated as a read only identification page intended to store serial numbers and similar information.

Actually interacting with the SPI flash then is accomplished via a set of dedicated instructions shown in the figure.

Eight bit instructions set the operational mode of the chip


Finally, keep in mind that ST also goes after the extremely lucrative I2C EEPROM market. Their offering for this market is called M24xxx. Both chip families are automotive certified, thereby permitting their usage in challenging environments.