We use the Bus Pirate to interface a new chip without writing code or creating a PCB. based on your feedback, and our experience using the original Bus Pirate to demonstrate various parts, we updated the design with new features and more affordable components.

There’s also a firmware update for both Bus Pirate hardware versions, with bug fixes, and a PC AT keyboard decoder. check out the new Hack a Day Bus Pirate page, and browse the Bus Pirate source code in our Google code SVN repository.

We cover the design updates and interface a digital to analog converter below.

Concept overview

The Bus Pirate started as a collection of code fragments we used to test new chips without limitless compile-program-run development cycles. We released it in a how-to and used it to demonstrate a bunch of serial interface ICs in our parts posts. This post introduces an updated design with new features and a bunch of improvements.

Surface mount design

Pull-up resistors on all bus lines with external voltage source

Software resettable 3.3volt and 5volt power supplies

Voltage monitoring of all power supplies

An external voltage measurement probe

Cheaper parts

Hardware

Click for a full size schematic image (PNG). The circuit and PCB are created using the freeware version of Cadsoft Eagle. All the files for this project are included in the project archive linked at the end of the article.

Microcontroller

We used a Microchip PIC24FJ64GA002 28pin SOIC microcontroller (IC1) in this project. The power pins have 0.1uF bypass capacitors to ground (C1,2). The 2.5volt internal regulator requires a 10uF tantalum capacitor (C20). The chip is programmed through a five pin header (ICSP). A 2K pull-up resistor (R1) is required for the MCLR function on pin 1. read a lot more about this chip in our PIC24F introduction.

RS-232 transceiver

An economical MAX3232CSE RS232 transceiver (IC2) interfaces the photo to a PC serial port. This chip replaces the expensive through-hole MAX3223EEPP+ used in the previous version of the Bus Pirate. The serial interface will work with a USB->serial adapter.

Bus pull-up resistors

The original Bus Pirate has 3.3volt pull-up resistors on 2 pins, but a lot of of our tests required additional external resistors. The updated design has pull-up resistors (R20-23) on the three main bus signals (data in, data out, clock) and the chip select (CS) pin.

A row of jumpers (SV5) connects each resistor to an external voltage supplied through the Vext terminal (X4). Through-hole resistors are used like jumper-wires to make the PCB much easier to etch at home.

We couldn’t find an sophisticated way to control an arbitrary voltage pull-up resistor variety from a 3.3volt microcontroller. If you have any ideas, please share them in the comments.

Strømforsyning

VR1 is a 3.3volt supply for the microcontroller and RS232 transceiver. VR2 is a 5volt supply. Both require two 0.1uF bypass capacitors (C3-C6). J1 is a power supply jack for a common 2.1mm DC barrel plug. 7-10volts DC is probably the optimal power supply range.

The original Bus Pirate had dual power supplies, 3.3volts and 5volts, so a lot of ICs could be interfaced without an additional power supply. A major nuisance was the lack of a power reset for connected chips. If a misconfigured IC needed to be power-cycled, we had to disconnect a wire. We got so worn out of this routine that we added a software controlled reset to the updated design.

VR3 (3.3volts) and VR4 (5volts) are TI TPS796XX voltage regulators with an enable switch. A high level on pin 1 enables the regulator. A pull-down resistor (R13,R12) makes sure that the regulators are off when the photo isn’t actively driving the line, such as during power-up initialization. The datasheet specifies a large capacitor on the input (C23, C21) and output (C24, C22) pins, we used the same 10uF tantalum we use everywhere. An additional, optional, 0.1uF capacitor (C12,C11) can improve regulation.

The switchable regulators are powered by VR2, a 5volt supply.  We did this because the maximum input for VR3 and VR4 is 6volts, leaving the device with a narrow 5.2-6volt power supply range. VR2 will work well above 10volts, and supplies an appropriate supply for the other regulators.

VR3 (3.3volts) has plenty of headroom to operate from a 5volt supply. VR4 (5volts) will lose about 0.2volts, but 4.8volts remains well within the acceptable range for a lot of 5volt chips. In practice, and under light loads, we see less than 0.1volts drop-out from VR4.

Voltage monitoring

Voltage monitoring is a new feature we’re really ecstatic about. has your project ever mysteriously stopped responding because of an accidental short circuit? The Bus Pirate’s power supplies are equipped with voltage monitoring that can discover a change in power levels.

Each monitored signal is connected to an analog to digital converter (ADC) through a resistor voltage divider. two 10K Modstande (R10, R11 ovenfor) Opdel indgangsspændingen i halvdelen, hvilket gør det muligt at måle op til 6,6volts med 3.3volt Photo Microcontroller.

Buspiraten har fire spændingsmonitorer. 3.3volt og 5volt strømforsyninger overvåges, ligesom den eksterne spænding føres til pull-up modstandene. En fjerde skærm er forbundet til PIN 9 af outputoverskriften for at gøre en spændingssonde.

PCB.

Klik for et fuld størrelse placeringsdiagram (PNG). Bestyrelsen er et tilsyneladende enkeltsidet design, vi ætsede vores i laboratoriet på en enkeltsidet fotoshåndtering PCB. På toppen, nær C13, møder to jumper ledninger i en enkelt VIA; Vi loddede en jumpertråd til den anden på bagsiden af ​​brættet.

Delliste

En del
Værdi

IC1.
Pic24fj64ga002 (soic)

IC2.
Max3232cse (soic-n)

Vr1.
LD1117S33 3.3volt regulator (SOT223)

VR2.
LD1117S50 5Volt regulator (SOT223)

VR3.
TPS79633 3.3volt regulator (SOT223-6)

VR4.
TPS79650 5Volt regulator (SOT223-6)

C1-13.
0,1uf kondensator (0805)

C20-24.
10uf tantalum kondensator (SMC A)

R1.
2000 ohm modstand (0805)

R2,3.
390 ohm modstand (0805)

R4-13.
10000 ohm modstand (0805)

R20-23.
2.2k-10k ohm modstand (gennemgående hul)

LED1,2.
LED (0805)

J1.
2.1mm power jack

X2, x4.
Skrueklemme (2 terminaler) * Untested

X3.
DB9 Kvinde Serial Port Connector * Untested

ICSP.
0,1 “PIN-overskrift, lige

Sv4.
0,1 “PIN-overskrift eller indhyllet header

Sv5.
0,1 “PIN-overskrift, lige

Firmware.

Firmware er skrevet i C ved hjælp af den gratis demonstrationsversion af billedet C30 compiler. Lær alt om at arbejde med dette billede i vores introduktion til billedet 24f serien.

Den nyeste firmware er indsendt på hack en dag bus pirat side. Den aktuelle kilde er i vores Google-kode SVN-depot.

Ved hjælp af det

Diagrammet ovenfor viser buspiratpinoutet.

Vi lavede en ledning med alligatorklip på enden og tilføjede etiketter til hver ledning, så vi ikke behøver at henvise til denne tabel, når vi interfaces en ny chip.

Hvis du kender til nogen fantastiske stik eller kabler, skal du linke til dem i kommentarerne.

LTC2640 SPI DIGITAL til analog spænding konverter

Den lineære teknologi LTC2640-LZ8 er en 8bit Digital til analog konverter (DAC) programmeret over SPI. En DAC er i det væsentlige en programmerbar spændingsdeler. De er gavnlige for at genskabe bølgeformer, såsom lydsignaler. En 8bit DAC har 255 selv intervaller mellem 0 og referencespændingen, den del vi anvendte har en intern 2.5voltreference.

LTC2640 kommer kun i en lille SOT223-8-pakke, så vi lavede en breadboard-adapter i profilen af ​​en DIP-8-chip. Vores LTC2640 fodspor er inkluderet i projektarkivet vedhæftet i slutningen af ​​denne artikel.

Den ovenfor beskrevne skematiske viser vores testkredsløb for LTC2640. Det kræver en 2,7-5volt strømforsyning, vi brugte bussen piratens 3.3volt forsyning. C1 er en bypass kondensator mellem strømstiften og jorden. PIN-kode 8 er en aktiv-low-nulstillingsstift, binde den høj til normal drift. Pin 7 er DAC-udgangen, tilslut buspiratspændingsmålingssonden (ADC) her.

Bus pirat.
LTC2640 (PIN #)

Mosi.
SDI (3)

UR
Sck (2)

Cs.
CS / LD (1)

ADC.
Vout (7)

+ 3.3volts.
CLR (8)

+ 3.3volts.
VDD (5)

Gnd.
GND (4)

Vi forbød bussen pirat til LTC2640 som vist i tabellen. LTC2640 har ikke en dataudgangsstift, denne SPI-forbindelse forbliver ubrugt.

Bus Pirat’s Hardware Spi Library og Software Raw3wire Bibliotek er kompatible med LTC2640s SPI interface. Vi brugte spi biblioteket; Hvis du bruger Raw3wire-biblioteket, skal du vælge normal PIN-udgang.

Hiz> m <-Vælg tilstand 1. Hiz. 2. 1-wire 3. UART. 4. I2C. 5. SPI. 6. JTAG. 7. RAW2Wire. 8. RAW3Wire. 9. PC på tastaturet Mode> 5 <-spi eller Raw3wire 900 MODE SET. Indstil hastighed: 1. 30kHz. 2. 125kHz. 3. 250kHz. 4. 1MHz. Hastighed> 1 <-Test ved lav hastighed ... 102 SPI Ready. Spi >.

Tryk på M for menuen Bus Pirate Mode, vælg 5 for SPI-tilstand. Der er en flok konfigurationsindstillinger for SPI-modulet, brug standardindstillingerne for dem alle. Når SPI-tilstand er klar, skal vi konfigurere strømforsyningen.

SPI> P <-Power Supply Setup W / w skifter 3.3volt forsyning? 1. Nr 2. Ja MODE> 2 <-USE 3.3Volt Supply W / w skifter 5voltforsyning? 1. Nr 2. Ja MODE> 1 <-DON'T brug 5Volt forsyning 9xx forsyning konfigureret, brug w / w til at skifte 9XX VOLTAGE MONITOR: 5V: 0,0 | 3.3V: 0,0 | Vpullup: 0,0 | Spi >.

P Åbner Bus Pirate Strømforsyningsmenuen. Vi bruger 3.3voltforsyningen, men ikke 5voltforsyningen. Spændingsskærmen verificerer, at strømforsyningerne er slukket.

Spi> w <-capital w (dumt CSS) muliggør strømforsyning 9xx 3.3volt forsyning på SPI> V <-Voltage Monitor 9XX VOLTAGE MONITOR: 5V: 0,0 | 3.3v: 3.3 | Vpullup: 0,0 | Spi >.

Kapital ‘W’ muliggør alle strømforsyninger, der er valgt i den forrige menu, en lille ‘W’ deaktiverer dem. V Viser forsyningsspændingsmonitoren, som nu viser 3.3volts udgang fra 3.3voltforsyningen.

Nu, at konfigurationen er færdig, kan vi sende kommandoer til LTC2640 over SPI-bussen. LTC2640 har en 24bit (3byte) interface-protokol. Den første byte er en kommando, efterfulgt af to databytes. LTC2640 fås i 8,10 og 12bit versioner; 8bit-versionen bruger den første byte til at indstille DAC VALUe, and ignores the second byte.

SPI>[0b00110000 255 0]<–set DAC to full 110 SPI CS ENABLED 120 SPI WRITE: 0x30<–write DAC command 120 SPI WRITE: 0xFF<–DAC value 120 SPI WRITE: 0x00<–don’t care 140 CS DISABLED Spi >.

Every SPI command begins by enabling the chip select pin ([). The first byte is the command to update the DAC (0b00110000), followed by the value to output (255), and a third byte that’s ignored (0). The command ends by disabling chip select (]).

We used an 8bit DAC with 255 even voltage steps, output set to 255 is 100%. We can use the Bus Pirate voltage probe to measure the output.

SPI>d<–measure voltage 9xx VOLTAGE PROBE: 2.5VOLTS<–DAC output Spi >.

D triggers a voltage measurement. The DAC output voltage is 100% (255/255) of the internal reference, 2.5volts.

SPI>[0b00110000 0 0] d
110 SPI CS ENABLED
120 SPI WRITE: 0x30<–write DAC command 120 SPI WRITE: 0x00<–DAC value 120 SPI WRITE: 0x00<–don’t care 140 CS DISABLED 9xx VOLTAGE PROBE: 0.0VOLTS<–DAC output Spi >.

The same command with a DAC value of 0 outputs 0% (0/255) of 2.5volts; 0volts.

SPI>[0b00110000 128 0] d
110 SPI CS ENABLED
120 SPI WRITE: 0x30<–write DAC command 120 SPI WRITE: 0x80<–DAC value 120 SPI WRITE: 0x00<–don’t care 140 CS DISABLED 9xx VOLTAGE PROBE: 1.2VOLTS<–DAC output Spi >.

A DAC value of 128 is about 50% (128/255) of the reference voltage, 1.2volts.

SPI>[0b01000000 0 0] d
110 SPI CS ENABLED
120 SPI WRITE: 0x40<–power down command 120 SPI WRITE: 0x00<–don’t care 120 SPI WRITE: 0x00<–don’t care 140 CS DISABLED 9xx VOLTAGE PROBE: 0.0VOLTS<–DAC off Spi >.

The LTC2640 has a low power mode, triggered by the command 0b01000000 and two bytes that are ignored. After the power down command we can verify that there’s output from the DAC. write any DAC value to exit low power mode.

Taking it further

What’s the next step for the Bus Pirate? We’ll eventually make a final update to the design that includes USB on a professionally made, double-sided PCB. Power supply indicator LEDs were slated for this version, but didn’t get included. It would also be helpful to have an AT  keyboard connector for debugging without a PC. check out the roadmap and wishlists on the Hack a Day Bus Pirate page.

Download: buspirate.v1a.zip