3.3.3. Maximum number of combined transactions Register

The max_comb_ot Register characteristics are:


The maximum combined outstanding transactions register enables you to program the maximum number of address requests for the AR and AW channels. The combined limit is applied after any individual channel limits. See Outstanding transaction regulation for more information.

The outstanding transaction limits have an integer part and a fractional part as follows:


Corresponds to the integer part.


Corresponds to the binary fraction.

A value of 0 for both the integer and fractional parts disables the programmable regulation so that the configuration limits apply.

A value of 0 for the fractional part programs disables the regulation of fractional outstanding transactions.

The regulation of the combined outstanding transaction limit also requires that you set the en_awar_ot control bit of the QoS control register. See QoS control Register and Table 3.2.

Usage constraints

You cannot increase the limit above either:

  • the configuration limits you set at design time

  • the CoreLink NIC-301 Network Interconnect limit of 64.


Only available when you select outstanding transaction regulation in AMBA Designer.


Figure 3.3 shows the bit assignments.

Figure 3.3. max_comb_ot Register bit assignments

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Table 3.4 shows the bit assignments.

Table 3.4. max_comb_ot Register bit assignments

[31:15]-Reserved. Do not modify. Read as zero.
[14:8]awar_max_otiInteger part of the maximum combined outstanding AW and AR addresses.
[7:0]awar_max_otfFractional part of the maximum combined outstanding AW and AR addresses.

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