Bus Pirate: Difference between revisions

Revision as of 13:53, 29 November 2012

Recovering a bricked SPI based device using a Bus Pirate

The Bus Pirate is an open source design for a multi-purpose chip-level serial protocol transceiver and debugger. Flashrom supports the Bus Pirate for SPI programming. It also has SPI sniffing functionality, which may come in useful for analysing chip or programmer behaviour.

They are available for around US$30 from various sources.

Connections

The table below shows how a typical SPI flash chip (sitting in the center of the table) needs to be connected (NB: not all flash chips feature all of the pins below, but in general you should always connect all input pins of ICs to some defined potential (usually GND or VCC), ideally with a pull-up/down resistor in between). Most SPI flash chips require a 3.3V supply voltage, but there exist some models that use e.g. 1.8V. Make sure the device in question is compatible before connecting any wires.

Description	Bus Pirate	Dir.	Flash chip				Dir.	Bus Pirate	Description
(not) Chip Select	CS	→	1	/CS	VCC	8	←	+3.3v	Supply
Master In, Slave Out	MISO	←	2	DO (IO1)	/HOLD	7	←	+3.3v	(not) hold (see datasheets)
(not) Write Protect	+3.3v	→	3	/WP (IO2)	CLK	6	←	+3.3v	The SPI clock
Ground	GND	→	4	GND	DI (IO0)	5	←	MOSI	Master Out, Slave In

Usage

$ flashrom -p buspirate_spi:dev=/dev/device,spispeed=frequency

Example:

$ flashrom -p buspirate_spi:dev=/dev/ttyUSB0,spispeed=1M

Troubleshooting

In case of problems probing the chip with flashrom - especially when connecting chips still soldered in a system - please take a look at this page. In circuit programming it often possible, so long as no other devices on the SPI bus are trying to access the device.

Speedup

A beta firmware build exists, to speed up the buspirate. See this post on dangerousprototypes.com: http://dangerousprototypes.com/forum/viewtopic.php?f=40&t=3864&start=15#p41505

http://dangerousprototypes.com/docs/Bus_Pirate#Firmware_upgrades

@@ Line 3: / Line 3: @@
 [[File:Lycom-pe115-flashrom-buspirate-2.jpg|thumb|right|<small>Recovering a bricked SPI based device using a Bus Pirate</small>]]
-The [http://dangerousprototypes.com/docs/Bus_Pirate Bus Pirate] is an open source design for a multi-purpose chip-level serial protocol transceiver and debugger. Flashrom supports the Bus Pirate for [http://dangerousprototypes.com/bus-pirate-manual/bus-pirate-spi-guide/ SPI programming]. It also has  [http://dangerousprototypes.com/docs/Bus_Pirate_binary_SPI_sniffer_utility SPI sniffing] functionality, which may come in useful for analysing chip or programmer behaviour.
+The [http://dangerousprototypes.com/docs/Bus_Pirate Bus Pirate] is an open source design for a multi-purpose chip-level serial protocol transceiver and debugger. Flashrom supports the Bus Pirate for [http://dangerousprototypes.com/docs/SPI SPI programming]. It also has  [http://dangerousprototypes.com/docs/Bus_Pirate_binary_SPI_sniffer_utility SPI sniffing] functionality, which may come in useful for analysing chip or programmer behaviour.
 They are available for around US$30 from various sources.
+==Connections==
+The table below shows how a typical SPI flash chip (sitting in the center of the table) needs to be connected (NB: not all flash chips feature all of the pins below, but in general you should always connect all input pins of ICs to some defined potential (usually GND or VCC), ideally with a pull-up/down resistor in between). Most SPI flash chips require a 3.3V supply voltage, but there exist some models that use e.g. 1.8V. Make sure the device in question is compatible before connecting any wires.
+{| style="border-collapse: collapse; border: 1px solid black;" cellpadding="5";  border="1" align="center"
+! Description
+! Bus Pirate
+! Dir.
+! colspan="4"|Flash chip
+! Dir.
+! Bus Pirate
+! Description
+|-
+| align="right" | (not) Chip Select    || CS    || <font size="+2">→</font> || style="background: #DDDDDD;" | 1 || align="left" style="background: #DDDDDD;" | /CS       || align="right" style="background: #DDDDDD;" | VCC      || style="background: #DDDDDD;" | 8 || <font size="+2">←</font> || +3.3v || align="left" | Supply
+|-
+| align="right" | Master In, Slave Out || MISO  || <font size="+2">←</font> || style="background: #DDDDDD;" | 2 || align="left" style="background: #DDDDDD;" | DO (IO1)  || align="right" style="background: #DDDDDD;" | /HOLD    || style="background: #DDDDDD;" | 7 || <font size="+2">←</font> || +3.3v || align="left" | (not) hold (see datasheets)
+|-
+| align="right" | (not) Write Protect  || +3.3v || <font size="+2">→</font> || style="background: #DDDDDD;" | 3 || align="left" style="background: #DDDDDD;" | /WP (IO2) || align="right" style="background: #DDDDDD;" | CLK      || style="background: #DDDDDD;" | 6 || <font size="+2">←</font> || +3.3v || align="left" | The SPI clock
+|-
+| align="right" | Ground               || GND   || <font size="+2">→</font> || style="background: #DDDDDD;" | 4 || align="left" style="background: #DDDDDD;" | GND       || align="right" style="background: #DDDDDD;" | DI (IO0) || style="background: #DDDDDD;" | 5 || <font size="+2">←</font> || MOSI  || align="left" | Master Out, Slave In
+|-
+|}
 == Usage ==
@@ Line 15: / Line 36: @@
   $ '''flashrom -p buspirate_spi:dev=/dev/ttyUSB0,spispeed=1M'''
-== Trouble Shooting ==
+== Troubleshooting ==
-The Bus Pirate has various options for SPI communication. Many SPI chips support the JEDEC standard identify command, which can be issued from the Bus Pirate prompt like this:
- [0x9f r:4]
-You'll need to refer to the flash chip datasheet to see how it should respond to this.
+In case of problems probing the chip with flashrom - especially when connecting chips still soldered in a system - please take a look at [[ISP|this page]].
 In circuit programming it often possible, '''so long as no other devices on the SPI bus are trying to access the device'''.
-See also [[ISP]] for more details about in-system flashing in general.
 == Speedup ==