
B-140
DSP56F801/803/805/807 User’s Manual
MOTOROLA
Preliminary
Application:
Date:
Programmer:
Sheet
C
B
HI8
HI8 Interface Control Register (ICR)
Bits
Name
Description
7INIT
Initialize
The Initialize bit is used by the host processor to force initialization of the HI8 hardware.
6
HM1
Host Mode Control
5HM0
The Host mode control bits HM0 and HM1 select the Transfer mode of the HI8. HM1 and HM0
enable the DMA mode of operation, or they interrupt a no-Host DMA mode of operation when
HREQ bit in the Host Control Register (HCR) is set.
4
HF1
Host Flag 1
The Host Flag 1 (HF1) bit is used as a general purpose flag for Host-to-DSP communication.
The HF1 bit can be set or cleared by the host processor, but cannot be changed by the DSP
core. The HF1 bit is cleared on DSP reset.
3
HF0
Host Flag 0
The Host Flag 0 (HF0) bit is used as a general purpose flag for Host-to-DSP communication.
The HF0 bit can be set or cleared by the host processor, but cannot be changed by the DSP
core. The HF0 bit is cleared on DSP reset.
2
HLEND
ICR Host Little Endian
This bit allows the HI8 to be accessed by the Host in or Big Endian data order. When the HLEND
bit is set, the HI8 can be accessed by the Host in Little Endian order. The RXH/TXH is located
at address $7 and RXL/TXL at $6. When the HLEND bit is cleared, the HI8 can be accessed by
the Host in Big Endian Host data order. The RXH/TXH is located at address $6 and RXL/TXL
at $7. The HLEND bit is cleared on hardware reset.
1
TREQ
ICR Transmit Request Enable
This bit is used to control the HREQ pin for Host transmit data transfers. In the Interrupt mode,
and the DMA is off, TREQ is used to enable interrupt requests via the external Host Request
(HREQ or HTRQ) pin when the TXDE status bit in the ISR is set. When TREQ is cleared, TXDE
interrupt is disabled.
0
RREQ
Receive Request Enable
This bit is used to control the HREQ pin for Host receive data transfers. In the Interrupt mode
(HDMA off), the RREQ is used to enable interrupt requests via the external Host Request
(HREQ or HRRQ) pin when the Receive Data Register Full (RXDF) status bit in the Interrupt
Status register (ISR) is set. When RREQ is cleared, RXDF interrupts are disabled. When RREQ
is set, the external Host Request HREQ pin or HRRQ is asserted if RXDF is set in interrupt
mode.
5 of 10
HI8 Interface
Control Register
(ICR)
$1FFFD8 + $0
Bits
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Read
0
INIT
HM1
HM0
HF1
HF0 HLEND TREQ RREQ
Write
0
RESET
0
000
00
0
denotes Reserved Bits