---
name: "dsp56k"
section: "4"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/dsp56k"
---

# dsp56k(4)

DSP56001 interface device

## NAME

dsp56k - DSP56001 interface device

## SYNOPSIS

```
#include <asm/dsp56k.h>
```

**ssize\_t read(int** *fd***, void \****data***, size\_t** *length***);** **ssize\_t write(int** *fd***, void \****data***, size\_t** *length***);**

**int ioctl(int** *fd***, DSP56K\_UPLOAD, struct dsp56k\_upload \****program***);** **int ioctl(int** *fd***, DSP56K\_SET\_TX\_WSIZE, int** *wsize***);** **int ioctl(int** *fd***, DSP56K\_SET\_RX\_WSIZE, int** *wsize***);** **int ioctl(int** *fd***, DSP56K\_HOST\_FLAGS, struct dsp56k\_host\_flags \****flags***);** **int ioctl(int** *fd***, DSP56K\_HOST\_CMD, int** *cmd***);**

## CONFIGURATION

The *dsp56k* device is a character device with major number 55 and minor number 0.

## DESCRIPTION

The Motorola DSP56001 is a fully programmable 24-bit digital signal processor found in Atari Falcon030-compatible computers. The *dsp56k* special file is used to control the DSP56001, and to send and receive data using the bidirectional handshaked host port.

To send a data stream to the signal processor, use [**write**(2)](/write/2.md) to the device, and [**read**(2)](/read/2.md) to receive processed data. The data can be sent or received in 8, 16, 24, or 32-bit quantities on the host side, but will always be seen as 24-bit quantities in the DSP56001.

The following [**ioctl**(2)](/ioctl/2.md) calls are used to control the *dsp56k* device:

- **DSP56K\_UPLOAD**

  resets the DSP56001 and uploads a program. The third [**ioctl**(2)](/ioctl/2.md) argument must be a pointer to a *struct dsp56k\_upload* with members *.bin* pointing to a DSP56001 binary program, and *.len* set to the length of the program, counted in 24-bit words.

- **DSP56K\_SET\_TX\_WSIZE**

  sets the transmit word size. Allowed values are in the range 1 to 4, and is the number of bytes that will be sent at a time to the DSP56001. These data quantities will either be padded with bytes containing zero, or truncated to fit the native 24-bit data format of the DSP56001.

- **DSP56K\_SET\_RX\_WSIZE**

  sets the receive word size. Allowed values are in the range 1 to 4, and is the number of bytes that will be received at a time from the DSP56001. These data quantities will either truncated, or padded with a null byte ('\\0'), to fit the native 24-bit data format of the DSP56001.

- **DSP56K\_HOST\_FLAGS**

  read and write the host flags. The host flags are four general-purpose bits that can be read by both the hosting computer and the DSP56001. Bits 0 and 1 can be written by the host, and bits 2 and 3 can be written by the DSP56001.

-

  To access the host flags, the third [**ioctl**(2)](/ioctl/2.md) argument must be a pointer to a *struct dsp56k\_host\_flags*. If bit 0 or 1 is set in the *.dir* member, the corresponding bit in *.out* will be written to the host flags. The state of all host flags will be returned in the lower four bits of the *.status* member.

- **DSP56K\_HOST\_CMD**

  sends a host command. Allowed values are in the range 0 to 31, and is a user-defined command handled by the program running in the DSP56001.

## FILES

*/dev/dsp56k*

## SEE ALSO

*linux/include/asm-m68k/dsp56k.h*, *linux/drivers/char/dsp56k.c*, ⟨http:\\://dsp56k.nocrew.org/⟩, DSP56000/DSP56001 Digital Signal Processor User's Manual