Datasheet

TMS320F28335, TMS320F28334, TMS320F28332
TMS320F28235, TMS320F28234, TMS320F28232
SPRS439M –JUNE 2007–REVISED AUGUST 2012 www.ti.com
6.14.9 XHOLD and XHOLDA Timing
If the HOLD mode bit is set while XHOLD and XHOLDA are both low (external bus accesses granted), the
XHOLDA signal is forced high (at the end of the current cycle) and the external interface is taken out of
high-impedance mode.
On a reset (XRS), the HOLD mode bit is set to 0. If the XHOLD signal is active low on a system reset, the
bus and all signal strobes must be in high-impedance mode, and the XHOLDA signal is also driven active
low.
When HOLD mode is enabled and XHOLDA is active low (external bus grant active), the CPU can still
execute code from internal memory. If an access is made to the external interface, the CPU is stalled until
the XHOLD signal is removed.
An external DMA request, when granted, places the following signals in a high-impedance mode:
XA[19:0] XZCS0
XD[31:0], XD[15:0] XZCS6
XWE0, XWE1, XZCS7
XRD
XR/W
All other signals not listed in this group remain in their default or functional operational modes during these
signal events.
166 Electrical Specifications Copyright © 2007–2012, Texas Instruments Incorporated
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