9797== SPI CLOCK RATES
9898
9999The maximum SPI clock of the BCM2835-SPI driver and the 7i90 is
100- documented over 32␗ ;MHz. The SPI driver can provide frequencies well
100+ documented over 32  ;MHz. The SPI driver can provide frequencies well
101101beyond what is acceptable for the 7i90. A safe value to start with would
102102be 12.5 MHz (spiclk_rate=12500) and then work your way up from there.
103103
@@ -107,22 +107,42 @@ The base frequency is 250 MHz and the divider for SPI0/SPI1 scales using
107107discrete factors. The following list specifies the *spiclk_rate* setting
108108and the discrete SPI clock frequency (250 MHz / (2__n__) for _n_ > 1):
109109
110- [cols=">,>"]
110+ :table-frame: ends
111+ :table-grid: none
112+ :table-option: header
113+
114+ .SPI clock rate and corresponding SPI clock frequency
115+ [cols="1,1,1"]
111116|===
112- | _n_ | Frequency range |
113- | 2 | 62500 - 62.500 MHz, |
114- | 3 | 41667 - 41.667 MHz, |
115- | 4 | 31250 - 31.250 MHz, |
116- | 5 | 25000 - 25.000 MHz, |
117- | 6 | 20834 - 20.833 MHz, |
118- | 7 | 17858 - 17.857 MHz, |
119- | 8 | 15625 - 15.625 MHz, |
120- | 9 | 13889 - 13.889 MHz, |
121- | 10 | 12500 - 12.500 MHz, |
122- | 11 | 11364 - 11.364 MHz, |
123- | 12 | 10417 - 10.417 MHz, |
124- | 13 | 9616 - 9.615 MHz, |
125- | 14+ | .... |
117+ ^| Divider
118+ ^| spiclk_rate (kHz)
119+ ^| actual frequency
120+
121+ | 2 | 62500 | 62.500 MHz
122+
123+ | 3 | 41667 | 41.667 MHz
124+
125+ | 4 | 31250 | 31.250 MHz
126+
127+ | 5 | 25000 | 25.000 MHz
128+
129+ | 6 | 20834 | 20.833 MHz
130+
131+ | 7 | 17858 | 17.857 MHz
132+
133+ | 8 | 15625 | 15.625 MHz
134+
135+ | 9 | 13889 | 13.889 MHz
136+
137+ | 10 | 12500 | 12.500 MHz
138+
139+ | 11 | 11364 | 11.364 MHz
140+
141+ | 12 | 10417 | 10.417 MHz
142+
143+ | 13 | 9616 | 9.615 MHz
144+
145+ | 14+ | ....
126146|===
127147
128148The lowest selectable SPI clock frequency is 30 kHz (spiclk_rate=30) for
@@ -143,8 +163,8 @@ Writing to the 7i90 may be done faster than reading. This is especially
143163important if you have "long" wires or any buffers on the SPI-bus path.
144164You can set the read clock frequency to a lower value (using
145165*spiclk_rate_rd*) to counter the effects of the SPI-bus round-trip
146- needed for read actions. For example, you can write at 41.67␗ ;MHz and
147- read at 25.00␗ ;MHz.
166+ needed for read actions. For example, you can write at 41.67  ;MHz and
167+ read at 25.00  ;MHz.
148168
149169It should be noted that the Rpi3 *must* have an adequate 5V power supply
150170and the power should be properly decoupled right on the 40-pin I/O
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