user3505: I'm trying to drive 16 of these little steppers on an Arduino Uno.
Each test driver uses 4 digital pins for control (2 for each coil) so that would be 64 pins I will need.
I'm thinking either getting something like this or 4 of these.
Would something like that work ?
What's the most straight forward way to drive these on an Arduino Uno ?

user313: If you need to drive all 16 simultaneously and independently, the Uno may not have enough capability to do it. Consider the worst-case number of motors and highest rate(s) you expect to drive at once, plus anything else you need the Uno doing at the same time. You might try a simple sketch to do all of these things (substituting LEDs for the motor drivers) at once, and use a scope to examine those LED output signals for the right frequency, wave-form, and lack of jitter. Without I/O expanders, you won't get to 16 motors' worth of outputs (unless you already have an I/O expander) but you might try doubling up on the existing output (use non-overlapping motor phases if you can).
If the Uno can manage that with clean outputs, you'll have a better idea whether it can manage the full load. If it doesn't, you may need to reconsider your choice of processor with respect to its clock-speed, both kinds of memory (depending on what you learned), number of outputs, possibly number of available timers and of interrupts.

3505: <p>I'm trying to drive 16 of these little <a href="https://www.amazon.co.uk/28BYJ-48-Stepper-ULN2003-Arduino-Raspberry/dp/B07857HCWN/ref=sr_1_6?s=electronics&amp;ie=UTF8&amp;qid=1527686132&amp;sr=1-6&amp;keywords=5v+stepper" rel="nofollow noreferrer">steppers</a> on an Arduino Uno.</p>

<p>Each test driver uses 4 digital pins for control (2 for each coil) so that would be 64 pins I will need.</p>

<p>I'm thinking either getting something like <a href="https://uk.farnell.com/macetech/mtcen001/centipede-shield-gpio-expander/dp/2804676?langId=44&amp;CMP=KNC-GUK-GEN-SHOPPING&amp;catalogId=15001&amp;storeId=10151&amp;storeId=10151&amp;krypto=pzWhyQJMteR7S5tpgdfh0160J%2BTS6ciZYF0%2FMAHkFV0hn5KvS3XeXtTtxa4MR4XJHizFO1kjn3awnXz3lLkWcjk%2FUoSzq558CKaBud8xr21N%2Fe4vL3nv6hw0nScKvdmburI7nFVUexkGx5bTIJXYf2Wg8CIHyjMD7Id%2BHLOosfa4gshkvBG8eUU35TnUItBMeRaqrFJWC%2B7LPgs5aM8ebMKLsrPF%2BKnKuI8R9JLH6t4EU5BMXH6ldjzUyQKOJJZH%2Fs5%2F9dORc59h%2FkWLOD6GtB0RiiJarK6PvtknLm%2FwhS2543RYRJJLDYmhPdw%2BKNXswjECe5zC1%2BLznJXT3nK4Bs5WmUpD%2BSUIBsvxQUIefnAmA5ZLVQO5ggsMNhmOoOx8gDfX7FGZrQ1mlUGwKUxmmV76eBzfkyf0eBGVyKERD%2F%2BbXrPgYnVb7Mr%2Ftob0uWHmFImcE1y0yiZRf90kpCWJyUXB4MO2s%2Bfa3cxDtrIQOFdSv%2BAHFJwJ3eXv8L2k4kEqi%2BSK77EUXkgeU7aiHUjHZs0k4gPlMfuu6ZvGGLRZPRv3NTwxW1CMQFRiWgwVXnKdPEUPDAnzEng0GpDd31VPSifqhxhrfhvYTAx2BfbqE8ZRqj%2BkQy9jcIi3XiZwrSY4MuYPJzCgy2nQNLzGqA1yjQ%3D%3D" rel="nofollow noreferrer">this</a> or 4 of <a href="https://coolcomponents.co.uk/products/16-output-i-o-expander-breakout-sx1509" rel="nofollow noreferrer">these</a>.</p>

<p>Would something like that work ?
What's the most straight forward way to drive these on an Arduino Uno ?</p>
 313: <p>If you need to drive all 16 simultaneously and independently, the Uno may not have enough capability to do it. Consider the worst-case number of motors and highest rate(s) you expect to drive at once, plus anything else you need the Uno doing at the same time. You might try a simple sketch to do all of these things (substituting LEDs for the motor drivers) at once, and use a scope to examine those LED output signals for the right frequency, wave-form, and lack of jitter. Without I/O expanders, you won't get to 16 motors' worth of outputs (unless you already have an I/O expander) but you might try doubling up on the existing output (use non-overlapping motor phases if you can).</p>

<p>If the Uno can manage that with clean outputs, you'll have a better idea whether it can manage the full load. If it doesn't, you may need to reconsider your choice of processor with respect to its clock-speed, both kinds of memory (depending on what you learned), number of outputs, possibly number of available timers and of interrupts.</p>
