8051 and 8052

The MIDI Drum Machine began in the Fall of 1991 as a project for a microprocessor system design course, shortly after I wrote PAULMON1, the 8051 monitor/debugger. A friend, Rod Seely, both a musician and electronics hobbiest suggested I design something using the Musical Instrument Device Interface, MIDI, that would be COOL and would work together with his collection of MIDI keyboards and synthesizers. Of course, I wanted to build something that could end up as a finished commercial product.

Inexpensive, 16-bit, monolithic DACs can serve almost all applications. However, some applications require unconventional approaches. This Design Idea design concerns circuitry I recently designed for a tunable-diode laser spectrometer for a Mars-exploration application. The control circuitry included two 16-bit DACs that interface to the radiation-hardened, 8051-variant 69RH051A microcontroller.

Below is a rough schematic of the layout of the accelerometer PC board looking from the component side. The microcontroller is an Atmel AT89S8252, an 8051 clone. This microcontroller is in-circuit programmable using an SPI interface. The SPI pins are also used to drive the MMC. To permit the dual use there is a jumper block (located below the 74AHC244, marked "P" and "R") that allows the pins to be connected for programming (P) or running the code (R).

The example program included with the PG2051 evaluation kit is a basic serial to parallel converter written in 8051 assembler. This is probably a good example of the uses to which an AT89C2051 can be put - it would be hard to get a serial to parallel converter much simpler than the single 20 pin IC in this circuit. The program is meant to serve as a useful example of 8051 serial routines and other programming, whether or not you actually need a serial to parallel converter.

In an 8051-based system without external program memory, the program-store enable (PSEN) pin is useless. However, you can indirectly control this pin using software. To do so, you execute the move-constant- (MOVC-) instruction-implementing table look-up. By accessing locations in external program memory (which is actually nonexistent), you can produce pulses on the PSEN line without disturbing program flow. Although you need a register for storing output data, you don’t have to install a decoder.

The 8051 series µCs offer idle and power-down modes, both of which you invoke by setting appropriate control bits from the code. For instance, a 5V, 12-MHz Atmel AT89C2051 consumes approximately 9 mA in active mode, 1.8 mA in idle mode, and only 12 µA in power-down mode. Although power-down savings outperform those of the idle mode by two orders of magnitude, the only way to restore the AT89C2051's operation from a power-down state is to reset, which constitutes a serious drawback for system designers.

I decided to rename C52EVB to be 8051SBC. Since the cpu can be any 8051 compatible chips with 40-pin DIP package. The old day chips, say 8031, 8751, 8032 or the new chips, 89C51, 89C52, 89C51RD2 can be used without any problem. Some may think that your old chips were useless, now you can use it for many projects. The monitor program of new 8051SBC was placed at external 32kB EPROM. With this space, you can customize your own monitor code or even add the application program and have the DIP switch to boot it when power up.

I decided to rename C52EVB to be 8051SBC. Since the cpu can be any 8051 compatible chips with 40-pin DIP package. The old day chips, say 8031, 8751, 8032 or the new chips, 89C51, 89C52, 89C51RD2 can be used without any problem. Some may think that your old chips were useless, now you can use it for many projects. The monitor program of new 8051SBC was placed at external 32kB EPROM. With this space, you can customize your own monitor code or even add the application program and have the DIP switch to boot it when power up.

This document describes the HSETI PCB. This PCB is a small simple application for the Atmel AT89C2051 microprocessor - a 20 pin 8051 variant, with FLASH (reprogrammable) program memory. The board has just two chips on it, the CPU and a driver/buffer.

Figure 1 shows an efficient and cost-effective frequency counter using an Atmel 89C2051 µC (Reference 1). The design can use any µC of the 8051 family. The circuit counts frequency and sends the count to a PC via the serial port. The signal connects to pin 3.4 of the µC. The TTL-compatible output of the µC drives the 1488, which converts the output to RS-232 voltage levels. The output of the 1488 connects to the RxD pin on the serial port of the PC.

A program entitled HEXBCD is an 8051 µC subroutine that converts a 16-bit HEX number in internal RAM locations 33 and 34H into its BCD equivalent (Listing 1). The program places the result in scratchpad registers R1, R2, and R3 . (You can download the file DI-SIG, #2120.)

When migrating assembly language programs from one family of microcontrollers to another, the first question is almost always: “What’s the equivalent opcode?” Some operations, like addition and subtraction, are self-evident and practically universal. Other instructions may have some subtle differences in syntax or spelling that make direct conversions a bit trickier. Occasionally, some instructions simply don’t have a direct equivalent in the target set, or an equivalent exists but is explained in different terms.

When migrating assembly language programs from one family of microcontrollers to another, the first question is almost always: “What’s the equivalent opcode?” Some operations, like addition and subtraction, are self-evident and practically universal. Other instructions may have some subtle differences in syntax or spelling that make direct conversions a bit trickier. Occasionally, some instructions simply don’t have a direct equivalent in the target set, or an equivalent exists but is explained in different terms. Another question that arises is that of addressing modes.

When migrating assembly language programs from one family of microcontrollers to another, the first question is almost always: ?What?s the equivalent opcode?? Some operations, like addition and subtraction, are self-evident and practically universal. Other instructions may have some subtle changes in syntax or spelling that make direct conversions a bit trickier.

The DS5000T (Dallas Semiconductors, www.dalsemi.com) is an 8051-compatible processor that integrates nonvolatile memory and a real-time clock. This module has an impressive set of functional extensions and security features, which makes it particularly useful for all-in-one embedded systems.

The 8052.com SBC is a single-board computer designed to be both useful and instructive in illustrating certain concepts commonly encountered in 8052-based development.

8051 Based TV Display: In the course of a recent 8052.com thread , using '51 variants as audio/video co-processors came up. In response, i spent last Sunday implementing a micro only solution for a modest 256 x 190 pixel monochrome video generator for an equally modest 5" monochrome TV.

this is a project i designed for a customer. it would have become a full on commercial project, but the client never went ahead and so it become GPL.

This is the complete schematic for the development board. Address and Data bus wires are drawn separately (not in a bus), so that it's easy to color over them on a printout, if you choose to manually connect the wires. It really is easier to buy a bare circuit board, though.

With the circuit design described here, any derivative of the 8051 microcontroller can communicate using the serial-infrared (SIR) format established by the Infrared Data Association (IrDA).