usbasp improved

WCID compliant, HID UART support

This USBasp firmware is based on a fork by Ralph Doncaster. Original fork readme can be found at README_nerdralph.md.

Features

• From version 1.07 a default SCK clock of 1.5Mhz and automatic SCK slowing if target does not respond. PORTD is left as input, so this firmware also works with USBISP modules. ( nerdralph )
• From version 1.08 the firmware is WCID compliant, meaning it should work on Windows without any driver or .inf install.
• From version 1.09 a ( reliable at 9600 Baud, with 120ms - 160ms intervals for higher speeds see note at UART HID protocol ) UART HID implementation is added for debugging purposes. USBasp will appear as a composite device with a WINUSB interface and a HID interface.
• From version 1.10 USBasp WCID switch to Microsoft OS 2.0 Descriptors. It seems that it play better with USB 3.0 ports.
• From version 1.11 USBasp supports updating it's serial number ( see USBaspHIDUART utility ) and also adds support for the AT89S51/2 ICs.

Avrdude

Note: Windows only .

Windows MSVC builds of avrdude, uses libwinusb instead of libusb, which doesn't support composite devices as this firmware implements. Please use a MINGW build ( i.e. avrdude-v8.0-windows_mingw-x64.zip ) .

UART GUI Client

From release v0.7.0, the libUSBUARTTerminal supports this firmware's HID UART implementation.

UART HID protocol

Note: There is a small 128 byte ring buffer for both Tx and Rx. That means you can use higher baud rates ( i.e. 115200 ) if the message length is smaller than 128 bytes and the transmit / receive interval is 160 ms or higher.

Serial Data

V-USB implementation uses 8 byte size input and output interrupt reports.

The last byte ( 8th ) has special meaning. Its serial data or its the serial bytes count. If its value is greater than 7 then its serial data. If the value is 7 or smaller then its the serial data count and the remaining bytes are ignored.

Input Reports ( USBasp -> USB PC ) or Output Reports ( USB PC -> USBasp)

i.e.

0x55,0x34,0x00,0x00,0x00,0x00,0x00,0x02 -> Actual serial bytes 2 : 0x55,0x34

0x00,0x34,0x00,0x66,0x32,0x36,0x00,0x04 -> Actual serial bytes 4 : 0x00,0x34,0x00,0x66

0x00,0xC3,0x34,0x55,0x32,0xF3,0x00,0xAB -> Actual serial bytes 8 ( 8th byte > 7 ) : 0x00,0xC3,0x34,0x55,0x32,0xF3,0x00,0xAB

UART Configuration

The USBasp's UART configuration uses an 8 byte size feature report, with the following format.

Byte 0	Byte 1	Byte 2	Byte 3	Byte 4 - 7 RO
Prescaler Low Byte	Prescaler High Byte	See UART Flags	Unused	USBasp Capabilities

To setup and enable the UART, send a feature set report, with the prescaler in the first two bytes and the parity, data bit, stop bit flags at the third byte ( see UART Flags ). The fourth byte is ignored.

To disable the UART, send a feature set report, with the prescaler bytes as zero.

Note: The UART is disabled by default, if read or write is detected for do to not interfere with those functions.

USBaspHIDUART utility

The USBaspHIDUART is a simple console utility, used for testing the HID UART implementation.

This is the help page ( USBaspHIDUART.exe -h ) :

USBaspHIDUART -h

USBasp HIDUART Test App

 -l  List USBasp HID devices
 -i  Select USBasp index ( default 0 )
 -b  Set Baud ( default 9600 )
 -c  Set USBasp Crystal Hz ( default 12 MHz or 12000000 Hz )
 -s  Select USBasp with serial number.
     4 Digits numeric only i.e. 3456, 2222, etc ).
 -u  Serial Number to update ( 4 Digits numeric only i.e. 3456, 2222, etc ).
     Use with index -i when more than one USBasp are connected.
 -r  Continuous read input
 -w  Interactive send output

examples

Read from USBasp at index 0 with 4800 baud
 USBaspHIDUART -b 4800 -r

Interactive write to USBasp at index 1 with 9600 baud
 USBaspHIDUART -i 1 -w

Interactive write to USBasp with serial number 1111 with 9600 baud
 USBaspHIDUART -s 1111 -w

Read from USBasp with 20 MHz crystal at index 1 with 19200 baud
 USBaspHIDUART -i 1 -b 19200 -c 20000000 -r

Read from USBasp with 20 MHz crystal and with serial number 2345 with 19200 baud
 USBaspHIDUART -s 2345 -b 19200 -c 20000000 -r

Update the first found USBasp's serial number with 3456
 USBaspHIDUART -u 3456

Update the USBasp's at index 3 serial number with 3456
 USBaspHIDUART -i 3 -u 3456

Build from source

Building USBaspHIDUART from source is very straightforward :

Note: You'll need FreePascal 3.0.4 and higher installed.

( it's always better to build in another directory )

Windows

<pathtocloneddir>\utility\USBaspHIDUART>mkdir build
<pathtocloneddir>\utility\USBaspHIDUART>cd build
<pathtocloneddir>\utility\USBaspHIDUART\build>fpc.exe -MObjFPC -FU. -Fu..\hidapi.pas ..\USBaspHIDUART.pas -o.\USBaspHIDUART.exe

Linux \ FreeBSD

<pathtocloneddir>\utility\USBaspHIDUART>mkdir build
<pathtocloneddir>\utility\USBaspHIDUART>cd build
<pathtocloneddir>\utility\USBaspHIDUART\build>fpc -MObjFPC -FU. -Fu../ -Fu../hidapi.pas -dUseCThreads ../USBaspHIDUART.pas -o./USBaspHIDUART