Serial Ee Prom Programming

Serial eeprom programmer, USB eeprom programmer and ISP for serial eeproms plus Atmel AT17xxx FPGA Configuration EEPROMs handheld serial eeprom programmer and usb univerasal programmer for programming serial Eeproms including DLL and Command line. Serial eeprom programmer, USB eeprom programmer and ISP for serial eeproms plus Atmel AT17xxx FPGA Configuration EEPROMs handheld serial eeprom.

Basic information about memory chips and programming We receive frequent inquiries on memory chips and are repeatedly forced to note that there is still a very high requirement for information in this area. For this reason, we are now making the basic information for programming memory chips, such as eproms/eeproms and Flash chips, public here. In particular, we will discuss the various types of memory chips and compare what the 27C, 28C or 29F series, for instance, can and cannot do. • • • • • • • • • • • What is a memory chip? A memory chip is an electronic component which can store a program, data or both. In this context, a program is a series of commands (command string) for a microprocessor (= computing unit). Data could consist, for instance, of temperature values taken by a temperature measurement system, or any other data.

The program / data is stored in the memory chip by a series of numbers - zeros and ones (=bits). A Bit can either be a zero (0) or a one (1).

It is difficult for a person to gain an overview over these Bits; therefore, they are gathered into groups. Sixteen bits are a 'Word', eight bits are a 'Byte' and four bits are a 'Nibble'. The most commonly used term is the Byte, which contains 8 bits and can accept 2 to the 8th power = 256 different values. In order to represent these, the hexadecimal number system is used.

This is based on a number of 16 and uses the digits 0 to 9 and additionally, A to F. Therefore, two digits can also accept 256 values (from 00h to FFh, wherein the small 'h' only identifies the hexadecimal number). We would like to direct those who need more precise information about the number systems to suitable other locations. The terms Kilo and Mega with regard to Bytes were also adapted to the binary nature (zero or one) of the digital systems. Here, Kilo means 1024 (= 2 to the 10th power) and Mega means 1024 * 1024 = 1048576. Therefore a Kilobyte is 1024 Bytes and a Megabyte is 1048576 Bytes.

Organization of a memory chip For the 8 Bit memory chips (the most common type) the Bits are put together in a Byte (= 8 bits) and stored under an 'address'. The Bytes can be accessed at this address and then the eight bits of the accessed address are output on its eight data ports. For example, in an 8-megabit chip like the 27c801, there are altogether 1048576 bytes (= 8388608 bits). Each Byte has its own address, numbered from 00000h through FFFFFh (corresponding to the decimal 0 to 1048575). Aside from the 8 Bit memory chips, there are also 16 Bit memory chips, serial 1-Bit memory chips and (rarely/old) 4 Bit chips. EPROM memory chips (27 / 27C.) EPROM stands for Erasable Programmable Read Only Memory.

What does this mean in detail? 'Erasable' means that the data on it can be removed. With these chips, erasure is carried out by exposure to intensive ultraviolet light in the area of 254 nm wavelength. We deal with erasing eproms with UV-C light in further detail below. 'Programmable' means that a program or data can be programmed (burned) into this chip.

For programming, a programming device such as the Batronix Eprommer or the Galep-4 is required. 'Read Only Memory' means that this type of memory can be read out but not programmed in the target device.

This memory type can be burned (programmed) by a programming device and then retains its data until an erasing device erases it. During the programming process, any desired number of bits from one to zero can be programmed. Eproms can also be programmed repeatedly without being erased as long as the bits are only changed from one to zero or remain on zero. To change a bit from zero to one, erasure is necessary. Since the quartz glass window required for erasing the chip with UV-C light is a big part of the production costs for the chip, this chip is available with and without this window. Without the window, the chip cannot be erased using UV-C light. The eproms with windows are also called UV eproms; the ones without are called OTP (=One Time Programmable) eproms.

After programming an erasable eprom with UV-C light, the glass window should be closed with a sticker so no sunlight can enter. Sunlight also contains components of UV-C light and can eventually erase data from the eprom. In the name of an EPROM, the 'C' after the 27 indicates that it is a CMOS EPROM (CMOS=Complimentary Metal Oxide Semiconductor). These require a much lower performance than the old NMOS EPROMS and can function with lower programming voltages (12.5 volts) (NMOS=N-channel Metal Oxide Semiconductor). Since both chips are otherwise compatible, the old NMOS EPROMS can be replaced with CMOS EPROMS of the same size (e.g. A 2764 can be replaced by a 27C64).